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LINK AGGREGATION CONFUSION LACP is part of the 802.1AX standard, but it is neither the entirety of the 802.1AX standard, nor is it required in order to stand up a LAG. LACP is also not link aggregation. It is a protocol to build LAGs automatically, versus static. You can usually build an 802.1AX LAGwithout using LACP.
ETHERNET CONGESTION: DROP IT OR PAUSE IT Ethernet has the ability to employ flow control on physical interfaces, so that when congestion is about to occur, the receiving port can signal to the sending port to stop sending for a period of time. This is referred to simply as 802.3x Ethernet flow control, or as I like to call it, old-timey flow control, as it’s been inEthernet since
DO WE NEED CHASSIS SWITCHES ANYMORE IN THE DC? Do We Need Chassis Switches Anymore in the DC? While Cisco Live this year was far more about the campus than the DC, Cisco did announce the Cisco Nexus 9364C, a spine-oriented switch which can run in both ACI mode and NX-OS mode. And it is a monster. It’s (64) ports of 100 Gigabit. It’s from a single SoC (the Cisco S6400 SoC). SSL: WHO DO YOU TRUST? Note: This is a post that appeared on the site lbdigest.com about a year or so ago, but given that SSL is back in the news lately, I figured it's worth updating and re-posting. Also, it features the greatest SSL diagram ever created. Seriously, if you fire up VXLAN: MILLIONS OR BILLIONS? I was putting slides together for my upcoming talk and there is some confusion about VXLAN in particular, how many VLANs it provides. The VXLAN header provides a 24-bit address space called the VNI (VXLAN Network Identifier) to separate out tenant segments, which is 16 million. And that's the number I see quoted with regards THE DATA CENTER OVERLORDS And SCSI is a high-maintenance payload. IP-based protocols have various recovery mechanisms at various levels if payloads are lost, or the protocols don’t care. SCSI does care if a message is lost, it cares a lot. Its recovery mechanisms are time consuming and still possible to end up with data corruption. ABOUT | THE DATA CENTER OVERLORDS I'm Tony Bourke. I'm a networking/systems instructor and course ware developer. I'm also a USPA rated skydiving instructor (AFF-I) and hold an FAI world record in skydiving. I'm a former condescending Unix administrator turned network instructor turned data center overlord. I also fly small planes for fun, jump out of planes for fun, run stupid CUT-THROUGH SWITCHING ISN’T A THING ANYMORE So, cut-through switching isn't a thing anymore. It hasn't been for a while really, though in the age of VXLAN, it's really not a thing. And of course with all things IT, there are exceptions. But by and large, Cut-through switching just isn't a thing. And it doesn't matter. Cut-through versus store-and-forward was a preference MICROSOFT STORAGE SPACES IS HOT GARBAGE FOR PARITY STORAGE I love parity storage. Whether it's traditional RAID 5/6, erasure coding, raidz/raid2z, whatever. It gives you redundancy on your data without requiring double the drives that mirroring or mirroring+stripping would require. The drawback is write performance is not as good as mirroring+stripping, but for my purposes (lots of video files, cold storage, etc.) parity is CREATING YOUR OWN SSL CERTIFICATE AUTHORITY (AND DUMPINGCREATING YOUR OWN SSL CERTIFICATE AUTHORITY (AND DUMPING SELF SIGNED CERTS)JAN 11TH, 2016: NEW YEAR! ALSO, THERE WAS A COMMENT BELOW ABOUT ADDING -SHA256 TO THE SIGNING (BOTH SELF-SIGNED AND CSR SIGNING) SINCE BROWSERS ARE...INSTALL ROOT CERTIFICATE INTO WORKSTATIONSFOR YOU LAPTOPS/DESKTOPS/WORKSTATIONS, YOU’LL NEED TO INSTALL THE ROOT CERTIFICATE INTO YOUR TRUSTED CERTIFICATE REPOSITORIES. THIS CAN GET A LITTL...CREATE A CERTIFICATE (DONE ONCE PER DEVICE)EVERY DEVICE THAT YOU WISH TO INSTALL A TRUSTED CERTIFICATE WILL NEED TO GO THROUGH THIS PROCESS. FIRST, JUST LIKE WITH THE ROOT CA STEP, YOU’LL NE... Jan 11th, 2016: New Year! Also, there was a comment below about adding -sha256 to the signing (both self-signed and CSR signing) sincebrowsers are
LINK AGGREGATION CONFUSION LACP is part of the 802.1AX standard, but it is neither the entirety of the 802.1AX standard, nor is it required in order to stand up a LAG. LACP is also not link aggregation. It is a protocol to build LAGs automatically, versus static. You can usually build an 802.1AX LAGwithout using LACP.
ETHERNET CONGESTION: DROP IT OR PAUSE IT Ethernet has the ability to employ flow control on physical interfaces, so that when congestion is about to occur, the receiving port can signal to the sending port to stop sending for a period of time. This is referred to simply as 802.3x Ethernet flow control, or as I like to call it, old-timey flow control, as it’s been inEthernet since
DO WE NEED CHASSIS SWITCHES ANYMORE IN THE DC? Do We Need Chassis Switches Anymore in the DC? While Cisco Live this year was far more about the campus than the DC, Cisco did announce the Cisco Nexus 9364C, a spine-oriented switch which can run in both ACI mode and NX-OS mode. And it is a monster. It’s (64) ports of 100 Gigabit. It’s from a single SoC (the Cisco S6400 SoC). SSL: WHO DO YOU TRUST? Note: This is a post that appeared on the site lbdigest.com about a year or so ago, but given that SSL is back in the news lately, I figured it's worth updating and re-posting. Also, it features the greatest SSL diagram ever created. Seriously, if you fire up VXLAN: MILLIONS OR BILLIONS? I was putting slides together for my upcoming talk and there is some confusion about VXLAN in particular, how many VLANs it provides. The VXLAN header provides a 24-bit address space called the VNI (VXLAN Network Identifier) to separate out tenant segments, which is 16 million. And that's the number I see quoted with regards THE DATA CENTER OVERLORDS And SCSI is a high-maintenance payload. IP-based protocols have various recovery mechanisms at various levels if payloads are lost, or the protocols don’t care. SCSI does care if a message is lost, it cares a lot. Its recovery mechanisms are time consuming and still possible to end up with data corruption.FIBRE CHANNEL
10 Gigabit Ethernet provides 1250 MB/s, providing true 10 Gigabit Ethernet, and not putting the slight overhead into the equation. So while 10 Gigabit Ethernet is true 10 Gigabit, 16 Gigabit Fibre Channel is actually 14 Gigabit Fibre Channel (14.025, to be ETHERCHANNEL AND PORT CHANNEL EtherChannel is mentioned once that I can see. So in the IOS world, it seems that EtherChannel is the technology, and port channel is the interface. In the Nexus world, port channel is used as the term for the technology and the individual interface, though sometimes EtherChannel is referenced. It’s likely that port channel ispreferred in
BEST EFFORT FIBRE CHANNEL Turning on Fibre Channel Class 9 (FC_BE, Best Effort) is easy on a Cisco MDS: The mode F turns the port into an F_Port (for an N_Port to plug into), and class 9 makes it class 9. The last command is an important one that most people forget: Turning on WRED (Weighted Random Early Detection). JUMBO FIBRE CHANNEL FRAMES Jumbo Fibre Channel Frames. In the world of Ethernet, jumbo frames (technically any Ethernet frame larger than 1,500 bytes) is often a recommendation for certain workloads, such as iSCSI, vMotion, backups, basically anything that doesn’t communicate with the Internet because of MTU issues. And in fact, MTU issues is one of the biggesthurdles
SSL: WHO DO YOU TRUST? Note: This is a post that appeared on the site lbdigest.com about a year or so ago, but given that SSL is back in the news lately, I figured it's worth updating and re-posting. Also, it features the greatest SSL diagram ever created. Seriously, if you fire up AES-NI: HARDWARE ENCRYPTION IN YOUR PROCESSOR AES-NI is an instruction set added to newer Intel processors that accelerate certain symmetric cryptographic functions, particularly those related to AES. It’s been making its way incrementally into Intel’s processors (desktop, server, mobile). Intel’s Xeon server processors got them in the 5600 series, however they were not in the7600
FIBRE CHANNEL AND ETHERNET: THE ODD COUPLE Ethernet (and TCP/IP on top of it) is meant to be flexible, mostly reliable, and lossy. You’ll probably get the Layer 2 frames and Layer 3 packets from one destination to another, but there’s no gurantee. Fibre Channel is meant to be inflexible (compared with Ethernet), absolutely reliable, and DID VMWARE VSPHERE 6.0 REMOVE THE LAYER 2 ADJACENCY I've seen this misconception a few times on message boards, reddit, and even comments on this blog: That Layer 2 adjacency is no longer required with vSphere 6.0, as VMware now supports Layer 3 vMotion. The (mis)perception is that you no longer need to stretch a Layer 2 domain between ESXi hosts. That is incorrect. TLS 1.2: THE NEW HOTNESS FOR LOAD BALANCERS Since most of the world’s websites have a load balancer terminate the SSL, we can update the load balancers with TLS 1.2 and take care of a major portion of the servers on the Internet. Right now, most of the load balancing vendors don’t support TLS 1.2. If asked, they’ll likely say that there’s been no demand for it sinceclients don
THE DATA CENTER OVERLORDS And SCSI is a high-maintenance payload. IP-based protocols have various recovery mechanisms at various levels if payloads are lost, or the protocols don’t care. SCSI does care if a message is lost, it cares a lot. Its recovery mechanisms are time consuming and still possible to end up with data corruption. ABOUT | THE DATA CENTER OVERLORDS I'm Tony Bourke. I'm a networking/systems instructor and course ware developer. I'm also a USPA rated skydiving instructor (AFF-I) and hold an FAI world record in skydiving. I'm a former condescending Unix administrator turned network instructor turned data center overlord. I also fly small planes for fun, jump out of planes for fun, run stupid CUT-THROUGH SWITCHING ISN’T A THING ANYMORE So, cut-through switching isn't a thing anymore. It hasn't been for a while really, though in the age of VXLAN, it's really not a thing. And of course with all things IT, there are exceptions. But by and large, Cut-through switching just isn't a thing. And it doesn't matter. Cut-through versus store-and-forward was a preference CREATING YOUR OWN SSL CERTIFICATE AUTHORITY (AND DUMPINGCREATING YOUR OWN SSL CERTIFICATE AUTHORITY (AND DUMPING SELF SIGNED CERTS)JAN 11TH, 2016: NEW YEAR! ALSO, THERE WAS A COMMENT BELOW ABOUT ADDING -SHA256 TO THE SIGNING (BOTH SELF-SIGNED AND CSR SIGNING) SINCE BROWSERS ARE...INSTALL ROOT CERTIFICATE INTO WORKSTATIONSFOR YOU LAPTOPS/DESKTOPS/WORKSTATIONS, YOU’LL NEED TO INSTALL THE ROOT CERTIFICATE INTO YOUR TRUSTED CERTIFICATE REPOSITORIES. THIS CAN GET A LITTL...CREATE A CERTIFICATE (DONE ONCE PER DEVICE)EVERY DEVICE THAT YOU WISH TO INSTALL A TRUSTED CERTIFICATE WILL NEED TO GO THROUGH THIS PROCESS. FIRST, JUST LIKE WITH THE ROOT CA STEP, YOU’LL NE... Jan 11th, 2016: New Year! Also, there was a comment below about adding -sha256 to the signing (both self-signed and CSR signing) sincebrowsers are
MICROSOFT STORAGE SPACES IS HOT GARBAGE FOR PARITY STORAGE I love parity storage. Whether it's traditional RAID 5/6, erasure coding, raidz/raid2z, whatever. It gives you redundancy on your data without requiring double the drives that mirroring or mirroring+stripping would require. The drawback is write performance is not as good as mirroring+stripping, but for my purposes (lots of video files, cold storage, etc.) parity is LINK AGGREGATION CONFUSION LACP is part of the 802.1AX standard, but it is neither the entirety of the 802.1AX standard, nor is it required in order to stand up a LAG. LACP is also not link aggregation. It is a protocol to build LAGs automatically, versus static. You can usually build an 802.1AX LAGwithout using LACP.
BEST EFFORT FIBRE CHANNEL Turning on Fibre Channel Class 9 (FC_BE, Best Effort) is easy on a Cisco MDS: The mode F turns the port into an F_Port (for an N_Port to plug into), and class 9 makes it class 9. The last command is an important one that most people forget: Turning on WRED (Weighted Random Early Detection). ETHERCHANNEL AND PORT CHANNEL EtherChannel is mentioned once that I can see. So in the IOS world, it seems that EtherChannel is the technology, and port channel is the interface. In the Nexus world, port channel is used as the term for the technology and the individual interface, though sometimes EtherChannel is referenced. It’s likely that port channel ispreferred in
DO WE NEED CHASSIS SWITCHES ANYMORE IN THE DC? Do We Need Chassis Switches Anymore in the DC? While Cisco Live this year was far more about the campus than the DC, Cisco did announce the Cisco Nexus 9364C, a spine-oriented switch which can run in both ACI mode and NX-OS mode. And it is a monster. It’s (64) ports of 100 Gigabit. It’s from a single SoC (the Cisco S6400 SoC). ETHERNET CONGESTION: DROP IT OR PAUSE IT Ethernet has the ability to employ flow control on physical interfaces, so that when congestion is about to occur, the receiving port can signal to the sending port to stop sending for a period of time. This is referred to simply as 802.3x Ethernet flow control, or as I like to call it, old-timey flow control, as it’s been inEthernet since
THE DATA CENTER OVERLORDS And SCSI is a high-maintenance payload. IP-based protocols have various recovery mechanisms at various levels if payloads are lost, or the protocols don’t care. SCSI does care if a message is lost, it cares a lot. Its recovery mechanisms are time consuming and still possible to end up with data corruption. ABOUT | THE DATA CENTER OVERLORDS I'm Tony Bourke. I'm a networking/systems instructor and course ware developer. I'm also a USPA rated skydiving instructor (AFF-I) and hold an FAI world record in skydiving. I'm a former condescending Unix administrator turned network instructor turned data center overlord. I also fly small planes for fun, jump out of planes for fun, run stupid CUT-THROUGH SWITCHING ISN’T A THING ANYMORE So, cut-through switching isn't a thing anymore. It hasn't been for a while really, though in the age of VXLAN, it's really not a thing. And of course with all things IT, there are exceptions. But by and large, Cut-through switching just isn't a thing. And it doesn't matter. Cut-through versus store-and-forward was a preference CREATING YOUR OWN SSL CERTIFICATE AUTHORITY (AND DUMPINGCREATING YOUR OWN SSL CERTIFICATE AUTHORITY (AND DUMPING SELF SIGNED CERTS)JAN 11TH, 2016: NEW YEAR! ALSO, THERE WAS A COMMENT BELOW ABOUT ADDING -SHA256 TO THE SIGNING (BOTH SELF-SIGNED AND CSR SIGNING) SINCE BROWSERS ARE...INSTALL ROOT CERTIFICATE INTO WORKSTATIONSFOR YOU LAPTOPS/DESKTOPS/WORKSTATIONS, YOU’LL NEED TO INSTALL THE ROOT CERTIFICATE INTO YOUR TRUSTED CERTIFICATE REPOSITORIES. THIS CAN GET A LITTL...CREATE A CERTIFICATE (DONE ONCE PER DEVICE)EVERY DEVICE THAT YOU WISH TO INSTALL A TRUSTED CERTIFICATE WILL NEED TO GO THROUGH THIS PROCESS. FIRST, JUST LIKE WITH THE ROOT CA STEP, YOU’LL NE... Jan 11th, 2016: New Year! Also, there was a comment below about adding -sha256 to the signing (both self-signed and CSR signing) sincebrowsers are
MICROSOFT STORAGE SPACES IS HOT GARBAGE FOR PARITY STORAGE I love parity storage. Whether it's traditional RAID 5/6, erasure coding, raidz/raid2z, whatever. It gives you redundancy on your data without requiring double the drives that mirroring or mirroring+stripping would require. The drawback is write performance is not as good as mirroring+stripping, but for my purposes (lots of video files, cold storage, etc.) parity is LINK AGGREGATION CONFUSION LACP is part of the 802.1AX standard, but it is neither the entirety of the 802.1AX standard, nor is it required in order to stand up a LAG. LACP is also not link aggregation. It is a protocol to build LAGs automatically, versus static. You can usually build an 802.1AX LAGwithout using LACP.
BEST EFFORT FIBRE CHANNEL Turning on Fibre Channel Class 9 (FC_BE, Best Effort) is easy on a Cisco MDS: The mode F turns the port into an F_Port (for an N_Port to plug into), and class 9 makes it class 9. The last command is an important one that most people forget: Turning on WRED (Weighted Random Early Detection). ETHERCHANNEL AND PORT CHANNEL EtherChannel is mentioned once that I can see. So in the IOS world, it seems that EtherChannel is the technology, and port channel is the interface. In the Nexus world, port channel is used as the term for the technology and the individual interface, though sometimes EtherChannel is referenced. It’s likely that port channel ispreferred in
DO WE NEED CHASSIS SWITCHES ANYMORE IN THE DC? Do We Need Chassis Switches Anymore in the DC? While Cisco Live this year was far more about the campus than the DC, Cisco did announce the Cisco Nexus 9364C, a spine-oriented switch which can run in both ACI mode and NX-OS mode. And it is a monster. It’s (64) ports of 100 Gigabit. It’s from a single SoC (the Cisco S6400 SoC). ETHERNET CONGESTION: DROP IT OR PAUSE IT Ethernet has the ability to employ flow control on physical interfaces, so that when congestion is about to occur, the receiving port can signal to the sending port to stop sending for a period of time. This is referred to simply as 802.3x Ethernet flow control, or as I like to call it, old-timey flow control, as it’s been inEthernet since
ETHERNET OVER FIBRE CHANNEL Since the 80's, Ethernet has dominated the networking world. The LAN, the WAN, and the MAN are all now dominated by Ethernet links. FIDDI, HIPPI, ATM, Frame Relay, they've all gone by the wayside. But there is one protocol that has stuck around to run alongside Ethernet, and that's Fibre Channel. While Fibre Channel has ETHERCHANNEL AND PORT CHANNEL EtherChannel is mentioned once that I can see. So in the IOS world, it seems that EtherChannel is the technology, and port channel is the interface. In the Nexus world, port channel is used as the term for the technology and the individual interface, though sometimes EtherChannel is referenced. It’s likely that port channel ispreferred in
FIBRE CHANNEL: WHAT IS IT GOOD FOR? Fibre Channel has a rather unique solution to network redundancy: Build two completely separate networks: SAN A and SAN B. Fibre Channel’s job is to provide two independent data paths to from the initiator to the target. From my article Fibre Channel and Ethernet. Also the greatest SAN diagram ever made. Most of the redundancy inFibre
AES-NI: HARDWARE ENCRYPTION IN YOUR PROCESSOR AES-NI is an instruction set added to newer Intel processors that accelerate certain symmetric cryptographic functions, particularly those related to AES. It’s been making its way incrementally into Intel’s processors (desktop, server, mobile). Intel’s Xeon server processors got them in the 5600 series, however they were not in the7600
NPV AND NPIV
NPIV and NPV are among the two most ill-named of acronyms I’ve come across in IT, especially since they sound very similar, yet do two fairly different things. NPIV is an industry-wide term and is short for N_Port ID Virtualization, and NPV is a Cisco SSL: WHO DO YOU TRUST? Note: This is a post that appeared on the site lbdigest.com about a year or so ago, but given that SSL is back in the news lately, I figured it's worth updating and re-posting. Also, it features the greatest SSL diagram ever created. Seriously, if you fire up VXLAN: MILLIONS OR BILLIONS? I was putting slides together for my upcoming talk and there is some confusion about VXLAN in particular, how many VLANs it provides. The VXLAN header provides a 24-bit address space called the VNI (VXLAN Network Identifier) to separate out tenant segments, which is 16 million. And that's the number I see quoted with regards HEALTH CHECKING ON LOAD BALANCERS: MORE ART THAN SCIENCE Health checking is of course the process where by the load balancer (or application delivery controller) does periodic checks on the servers to make sure they’re up and responding. If a server is down for any reason, the load balancer should detect this and stop sending traffic its way. Pretty simple functionality, really. INEXPENSIVE VMWARE ESXI (VSPHERE HYPERVISOR) HOST Hi there, This is Raj from India. I first tried to buy an Intel i5 processor and that was upsetting me with the cost. They said it would cost around 40000 Rupees (740 USD) or better still i7 processor at nearly 50000 Rupees (925 USD) But I felt I would really spend a Bomb on it and switched over to AMD instead and Hey Presto I had to pay only 35000 Rupees (648 USD) to buy AMD FX with 8 TLS 1.2: THE NEW HOTNESS FOR LOAD BALANCERS Since most of the world’s websites have a load balancer terminate the SSL, we can update the load balancers with TLS 1.2 and take care of a major portion of the servers on the Internet. Right now, most of the load balancing vendors don’t support TLS 1.2. If asked, they’ll likely say that there’s been no demand for it sinceclients don
THE DATA CENTER OVERLORDS And SCSI is a high-maintenance payload. IP-based protocols have various recovery mechanisms at various levels if payloads are lost, or the protocols don’t care. SCSI does care if a message is lost, it cares a lot. Its recovery mechanisms are time consuming and still possible to end up with data corruption. ABOUT | THE DATA CENTER OVERLORDS I'm Tony Bourke. I'm a networking/systems instructor and course ware developer. I'm also a USPA rated skydiving instructor (AFF-I) and hold an FAI world record in skydiving. I'm a former condescending Unix administrator turned network instructor turned data center overlord. I also fly small planes for fun, jump out of planes for fun, run stupid CUT-THROUGH SWITCHING ISN’T A THING ANYMORE So, cut-through switching isn't a thing anymore. It hasn't been for a while really, though in the age of VXLAN, it's really not a thing. And of course with all things IT, there are exceptions. But by and large, Cut-through switching just isn't a thing. And it doesn't matter. Cut-through versus store-and-forward was a preference DO WE NEED CHASSIS SWITCHES ANYMORE IN THE DC? Do We Need Chassis Switches Anymore in the DC? While Cisco Live this year was far more about the campus than the DC, Cisco did announce the Cisco Nexus 9364C, a spine-oriented switch which can run in both ACI mode and NX-OS mode. And it is a monster. It’s (64) ports of 100 Gigabit. It’s from a single SoC (the Cisco S6400 SoC). ETHERNET OVER FIBRE CHANNEL Since the 80's, Ethernet has dominated the networking world. The LAN, the WAN, and the MAN are all now dominated by Ethernet links. FIDDI, HIPPI, ATM, Frame Relay, they've all gone by the wayside. But there is one protocol that has stuck around to run alongside Ethernet, and that's Fibre Channel. While Fibre Channel has ZFS ON LINUX WITH ENCRYPTION PART 2: THE COMPILING First off: Warning. I don't know what the stability of this feature is. It's been in the code for a couple of months, it hasn't been widely used. I've been testing it, and so far it's worked as expected. In exploring native encryption, I attempted to get it on Linux/ZFS using the instruction on this MICROSOFT STORAGE SPACES IS HOT GARBAGE FOR PARITY STORAGE I love parity storage. Whether it's traditional RAID 5/6, erasure coding, raidz/raid2z, whatever. It gives you redundancy on your data without requiring double the drives that mirroring or mirroring+stripping would require. The drawback is write performance is not as good as mirroring+stripping, but for my purposes (lots of video files, cold storage, etc.) parity is ETHERCHANNEL AND PORT CHANNEL EtherChannel is mentioned once that I can see. So in the IOS world, it seems that EtherChannel is the technology, and port channel is the interface. In the Nexus world, port channel is used as the term for the technology and the individual interface, though sometimes EtherChannel is referenced. It’s likely that port channel ispreferred in
LINK AGGREGATION CONFUSION LACP is part of the 802.1AX standard, but it is neither the entirety of the 802.1AX standard, nor is it required in order to stand up a LAG. LACP is also not link aggregation. It is a protocol to build LAGs automatically, versus static. You can usually build an 802.1AX LAGwithout using LACP.
BEST EFFORT FIBRE CHANNEL Turning on Fibre Channel Class 9 (FC_BE, Best Effort) is easy on a Cisco MDS: The mode F turns the port into an F_Port (for an N_Port to plug into), and class 9 makes it class 9. The last command is an important one that most people forget: Turning on WRED (Weighted Random Early Detection). THE DATA CENTER OVERLORDS And SCSI is a high-maintenance payload. IP-based protocols have various recovery mechanisms at various levels if payloads are lost, or the protocols don’t care. SCSI does care if a message is lost, it cares a lot. Its recovery mechanisms are time consuming and still possible to end up with data corruption. ABOUT | THE DATA CENTER OVERLORDS I'm Tony Bourke. I'm a networking/systems instructor and course ware developer. I'm also a USPA rated skydiving instructor (AFF-I) and hold an FAI world record in skydiving. I'm a former condescending Unix administrator turned network instructor turned data center overlord. I also fly small planes for fun, jump out of planes for fun, run stupid CUT-THROUGH SWITCHING ISN’T A THING ANYMORE So, cut-through switching isn't a thing anymore. It hasn't been for a while really, though in the age of VXLAN, it's really not a thing. And of course with all things IT, there are exceptions. But by and large, Cut-through switching just isn't a thing. And it doesn't matter. Cut-through versus store-and-forward was a preference DO WE NEED CHASSIS SWITCHES ANYMORE IN THE DC? Do We Need Chassis Switches Anymore in the DC? While Cisco Live this year was far more about the campus than the DC, Cisco did announce the Cisco Nexus 9364C, a spine-oriented switch which can run in both ACI mode and NX-OS mode. And it is a monster. It’s (64) ports of 100 Gigabit. It’s from a single SoC (the Cisco S6400 SoC). ETHERNET OVER FIBRE CHANNEL Since the 80's, Ethernet has dominated the networking world. The LAN, the WAN, and the MAN are all now dominated by Ethernet links. FIDDI, HIPPI, ATM, Frame Relay, they've all gone by the wayside. But there is one protocol that has stuck around to run alongside Ethernet, and that's Fibre Channel. While Fibre Channel has ZFS ON LINUX WITH ENCRYPTION PART 2: THE COMPILING First off: Warning. I don't know what the stability of this feature is. It's been in the code for a couple of months, it hasn't been widely used. I've been testing it, and so far it's worked as expected. In exploring native encryption, I attempted to get it on Linux/ZFS using the instruction on this MICROSOFT STORAGE SPACES IS HOT GARBAGE FOR PARITY STORAGE I love parity storage. Whether it's traditional RAID 5/6, erasure coding, raidz/raid2z, whatever. It gives you redundancy on your data without requiring double the drives that mirroring or mirroring+stripping would require. The drawback is write performance is not as good as mirroring+stripping, but for my purposes (lots of video files, cold storage, etc.) parity is ETHERCHANNEL AND PORT CHANNEL EtherChannel is mentioned once that I can see. So in the IOS world, it seems that EtherChannel is the technology, and port channel is the interface. In the Nexus world, port channel is used as the term for the technology and the individual interface, though sometimes EtherChannel is referenced. It’s likely that port channel ispreferred in
LINK AGGREGATION CONFUSION LACP is part of the 802.1AX standard, but it is neither the entirety of the 802.1AX standard, nor is it required in order to stand up a LAG. LACP is also not link aggregation. It is a protocol to build LAGs automatically, versus static. You can usually build an 802.1AX LAGwithout using LACP.
BEST EFFORT FIBRE CHANNEL Turning on Fibre Channel Class 9 (FC_BE, Best Effort) is easy on a Cisco MDS: The mode F turns the port into an F_Port (for an N_Port to plug into), and class 9 makes it class 9. The last command is an important one that most people forget: Turning on WRED (Weighted Random Early Detection). THE DATA CENTER OVERLORDS And SCSI is a high-maintenance payload. IP-based protocols have various recovery mechanisms at various levels if payloads are lost, or the protocols don’t care. SCSI does care if a message is lost, it cares a lot. Its recovery mechanisms are time consuming and still possible to end up with data corruption.REQUIEM FOR FCOE
Requiem for FCoE. FCoE is dead. We’re beyond the point of even asking if FCoE is dead, we all know it just is. It was never widely adopted and it’s likely never going to be widely adopted. It enjoy a few awkward deployments here and there, and a few isolated islands in the overall data center market, but it it never caught on the way itwas
ETHERCHANNEL AND PORT CHANNEL EtherChannel is mentioned once that I can see. So in the IOS world, it seems that EtherChannel is the technology, and port channel is the interface. In the Nexus world, port channel is used as the term for the technology and the individual interface, though sometimes EtherChannel is referenced. It’s likely that port channel ispreferred in
CHANGING DATA CENTER WORKLOADS Networking-wise, I've spent my career in the data center. I'm pursuing the CCIE Data Center. I study virtualization, storage, and DC networking. Right now, the landscape in the network is constantly changing, as it has been for the past 15 years. However, with SDN, merchant silicon, overlay networks, and more, the rate of change in ETHERNET CONGESTION: DROP IT OR PAUSE IT Ethernet has the ability to employ flow control on physical interfaces, so that when congestion is about to occur, the receiving port can signal to the sending port to stop sending for a period of time. This is referred to simply as 802.3x Ethernet flow control, or as I like to call it, old-timey flow control, as it’s been inEthernet since
SSL: WHO DO YOU TRUST? Note: This is a post that appeared on the site lbdigest.com about a year or so ago, but given that SSL is back in the news lately, I figured it's worth updating and re-posting. Also, it features the greatest SSL diagram ever created. Seriously, if you fire up CREATING YOUR OWN SSL CERTIFICATE AUTHORITY (AND DUMPING Jan 11th, 2016: New Year! Also, there was a comment below about adding -sha256 to the signing (both self-signed and CSR signing) sincebrowsers are
HEALTH CHECKING ON LOAD BALANCERS: MORE ART THAN SCIENCE Health checking is of course the process where by the load balancer (or application delivery controller) does periodic checks on the servers to make sure they’re up and responding. If a server is down for any reason, the load balancer should detect this and stop sending traffic its way. Pretty simple functionality, really. INEXPENSIVE VMWARE ESXI (VSPHERE HYPERVISOR) HOST Hi there, This is Raj from India. I first tried to buy an Intel i5 processor and that was upsetting me with the cost. They said it would cost around 40000 Rupees (740 USD) or better still i7 processor at nearly 50000 Rupees (925 USD) But I felt I would really spend a Bomb on it and switched over to AMD instead and Hey Presto I had to pay only 35000 Rupees (648 USD) to buy AMD FX with 8 TLS 1.2: THE NEW HOTNESS FOR LOAD BALANCERS Since most of the world’s websites have a load balancer terminate the SSL, we can update the load balancers with TLS 1.2 and take care of a major portion of the servers on the Internet. Right now, most of the load balancing vendors don’t support TLS 1.2. If asked, they’ll likely say that there’s been no demand for it sinceclients don
THE DATA CENTER OVERLORDS And SCSI is a high-maintenance payload. IP-based protocols have various recovery mechanisms at various levels if payloads are lost, or the protocols don’t care. SCSI does care if a message is lost, it cares a lot. Its recovery mechanisms are time consuming and still possible to end up with data corruption. ABOUT | THE DATA CENTER OVERLORDS I'm Tony Bourke. I'm a networking/systems instructor and course ware developer. I'm also a USPA rated skydiving instructor (AFF-I) and hold an FAI world record in skydiving. I'm a former condescending Unix administrator turned network instructor turned data center overlord. I also fly small planes for fun, jump out of planes for fun, run stupidREQUIEM FOR FCOE
Requiem for FCoE. FCoE is dead. We’re beyond the point of even asking if FCoE is dead, we all know it just is. It was never widely adopted and it’s likely never going to be widely adopted. It enjoy a few awkward deployments here and there, and a few isolated islands in the overall data center market, but it it never caught on the way itwas
CUT-THROUGH SWITCHING ISN’T A THING ANYMORE So, cut-through switching isn't a thing anymore. It hasn't been for a while really, though in the age of VXLAN, it's really not a thing. And of course with all things IT, there are exceptions. But by and large, Cut-through switching just isn't a thing. And it doesn't matter. Cut-through versus store-and-forward was a preferenceFIBRE CHANNEL
10 Gigabit Ethernet provides 1250 MB/s, providing true 10 Gigabit Ethernet, and not putting the slight overhead into the equation. So while 10 Gigabit Ethernet is true 10 Gigabit, 16 Gigabit Fibre Channel is actually 14 Gigabit Fibre Channel (14.025, to be DO WE NEED CHASSIS SWITCHES ANYMORE IN THE DC? Do We Need Chassis Switches Anymore in the DC? While Cisco Live this year was far more about the campus than the DC, Cisco did announce the Cisco Nexus 9364C, a spine-oriented switch which can run in both ACI mode and NX-OS mode. And it is a monster. It’s (64) ports of 100 Gigabit. It’s from a single SoC (the Cisco S6400 SoC). MICROSOFT STORAGE SPACES IS HOT GARBAGE FOR PARITY STORAGE I love parity storage. Whether it's traditional RAID 5/6, erasure coding, raidz/raid2z, whatever. It gives you redundancy on your data without requiring double the drives that mirroring or mirroring+stripping would require. The drawback is write performance is not as good as mirroring+stripping, but for my purposes (lots of video files, cold storage, etc.) parity is ETHERCHANNEL AND PORT CHANNEL EtherChannel is mentioned once that I can see. So in the IOS world, it seems that EtherChannel is the technology, and port channel is the interface. In the Nexus world, port channel is used as the term for the technology and the individual interface, though sometimes EtherChannel is referenced. It’s likely that port channel ispreferred in
LINK AGGREGATION CONFUSION LACP is part of the 802.1AX standard, but it is neither the entirety of the 802.1AX standard, nor is it required in order to stand up a LAG. LACP is also not link aggregation. It is a protocol to build LAGs automatically, versus static. You can usually build an 802.1AX LAGwithout using LACP.
BEST EFFORT FIBRE CHANNEL Turning on Fibre Channel Class 9 (FC_BE, Best Effort) is easy on a Cisco MDS: The mode F turns the port into an F_Port (for an N_Port to plug into), and class 9 makes it class 9. The last command is an important one that most people forget: Turning on WRED (Weighted Random Early Detection). THE DATA CENTER OVERLORDS And SCSI is a high-maintenance payload. IP-based protocols have various recovery mechanisms at various levels if payloads are lost, or the protocols don’t care. SCSI does care if a message is lost, it cares a lot. Its recovery mechanisms are time consuming and still possible to end up with data corruption. ABOUT | THE DATA CENTER OVERLORDS I'm Tony Bourke. I'm a networking/systems instructor and course ware developer. I'm also a USPA rated skydiving instructor (AFF-I) and hold an FAI world record in skydiving. I'm a former condescending Unix administrator turned network instructor turned data center overlord. I also fly small planes for fun, jump out of planes for fun, run stupidREQUIEM FOR FCOE
Requiem for FCoE. FCoE is dead. We’re beyond the point of even asking if FCoE is dead, we all know it just is. It was never widely adopted and it’s likely never going to be widely adopted. It enjoy a few awkward deployments here and there, and a few isolated islands in the overall data center market, but it it never caught on the way itwas
CUT-THROUGH SWITCHING ISN’T A THING ANYMORE So, cut-through switching isn't a thing anymore. It hasn't been for a while really, though in the age of VXLAN, it's really not a thing. And of course with all things IT, there are exceptions. But by and large, Cut-through switching just isn't a thing. And it doesn't matter. Cut-through versus store-and-forward was a preferenceFIBRE CHANNEL
10 Gigabit Ethernet provides 1250 MB/s, providing true 10 Gigabit Ethernet, and not putting the slight overhead into the equation. So while 10 Gigabit Ethernet is true 10 Gigabit, 16 Gigabit Fibre Channel is actually 14 Gigabit Fibre Channel (14.025, to be DO WE NEED CHASSIS SWITCHES ANYMORE IN THE DC? Do We Need Chassis Switches Anymore in the DC? While Cisco Live this year was far more about the campus than the DC, Cisco did announce the Cisco Nexus 9364C, a spine-oriented switch which can run in both ACI mode and NX-OS mode. And it is a monster. It’s (64) ports of 100 Gigabit. It’s from a single SoC (the Cisco S6400 SoC). MICROSOFT STORAGE SPACES IS HOT GARBAGE FOR PARITY STORAGE I love parity storage. Whether it's traditional RAID 5/6, erasure coding, raidz/raid2z, whatever. It gives you redundancy on your data without requiring double the drives that mirroring or mirroring+stripping would require. The drawback is write performance is not as good as mirroring+stripping, but for my purposes (lots of video files, cold storage, etc.) parity is ETHERCHANNEL AND PORT CHANNEL EtherChannel is mentioned once that I can see. So in the IOS world, it seems that EtherChannel is the technology, and port channel is the interface. In the Nexus world, port channel is used as the term for the technology and the individual interface, though sometimes EtherChannel is referenced. It’s likely that port channel ispreferred in
LINK AGGREGATION CONFUSION LACP is part of the 802.1AX standard, but it is neither the entirety of the 802.1AX standard, nor is it required in order to stand up a LAG. LACP is also not link aggregation. It is a protocol to build LAGs automatically, versus static. You can usually build an 802.1AX LAGwithout using LACP.
BEST EFFORT FIBRE CHANNEL Turning on Fibre Channel Class 9 (FC_BE, Best Effort) is easy on a Cisco MDS: The mode F turns the port into an F_Port (for an N_Port to plug into), and class 9 makes it class 9. The last command is an important one that most people forget: Turning on WRED (Weighted Random Early Detection). THE DATA CENTER OVERLORDS And SCSI is a high-maintenance payload. IP-based protocols have various recovery mechanisms at various levels if payloads are lost, or the protocols don’t care. SCSI does care if a message is lost, it cares a lot. Its recovery mechanisms are time consuming and still possible to end up with data corruption. ETHERCHANNEL AND PORT CHANNEL EtherChannel is mentioned once that I can see. So in the IOS world, it seems that EtherChannel is the technology, and port channel is the interface. In the Nexus world, port channel is used as the term for the technology and the individual interface, though sometimes EtherChannel is referenced. It’s likely that port channel ispreferred in
CHANGING DATA CENTER WORKLOADS Networking-wise, I've spent my career in the data center. I'm pursuing the CCIE Data Center. I study virtualization, storage, and DC networking. Right now, the landscape in the network is constantly changing, as it has been for the past 15 years. However, with SDN, merchant silicon, overlay networks, and more, the rate of change in VXLAN: MILLIONS OR BILLIONS? I was putting slides together for my upcoming talk and there is some confusion about VXLAN in particular, how many VLANs it provides. The VXLAN header provides a 24-bit address space called the VNI (VXLAN Network Identifier) to separate out tenant segments, which is 16 million. And that's the number I see quoted with regards SSL: WHO DO YOU TRUST? Note: This is a post that appeared on the site lbdigest.com about a year or so ago, but given that SSL is back in the news lately, I figured it's worth updating and re-posting. Also, it features the greatest SSL diagram ever created. Seriously, if you fire up ETHERNET CONGESTION: DROP IT OR PAUSE IT Ethernet has the ability to employ flow control on physical interfaces, so that when congestion is about to occur, the receiving port can signal to the sending port to stop sending for a period of time. This is referred to simply as 802.3x Ethernet flow control, or as I like to call it, old-timey flow control, as it’s been inEthernet since
CREATING YOUR OWN SSL CERTIFICATE AUTHORITY (AND DUMPING Jan 11th, 2016: New Year! Also, there was a comment below about adding -sha256 to the signing (both self-signed and CSR signing) sincebrowsers are
TLS 1.2: THE NEW HOTNESS FOR LOAD BALANCERS Since most of the world’s websites have a load balancer terminate the SSL, we can update the load balancers with TLS 1.2 and take care of a major portion of the servers on the Internet. Right now, most of the load balancing vendors don’t support TLS 1.2. If asked, they’ll likely say that there’s been no demand for it sinceclients don
HEALTH CHECKING ON LOAD BALANCERS: MORE ART THAN SCIENCE Health checking is of course the process where by the load balancer (or application delivery controller) does periodic checks on the servers to make sure they’re up and responding. If a server is down for any reason, the load balancer should detect this and stop sending traffic its way. Pretty simple functionality, really. INEXPENSIVE VMWARE ESXI (VSPHERE HYPERVISOR) HOST Hi there, This is Raj from India. I first tried to buy an Intel i5 processor and that was upsetting me with the cost. They said it would cost around 40000 Rupees (740 USD) or better still i7 processor at nearly 50000 Rupees (925 USD) But I felt I would really spend a Bomb on it and switched over to AMD instead and Hey Presto I had to pay only 35000 Rupees (648 USD) to buy AMD FX with 8 THE DATA CENTER OVERLORDS Where servers, storage and networking combine to form Voltron.Search:
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WOW: NVME AND PCIE GEN 4 September 16, 2019 Leave a comment Recently it’d come to my attention that my old PC rig wasn’tcutting it.
* Intel i7 950
* 18 GB of RAM
* X58 Asus-based motherboard* Sandisk 1 TB SSD
* 2 x 8 TB Shucked Best Buy Easystore Hard Drives in Windows Storage Spaces (see why I didn’t do parity storage because of the Microsoftshit-show
)
* 1 Gigabit Intel NIC* NVidia GTX 980
Considering it was 10 years old, it was doing really well. I mean, I went from HDD to 500 GB SSD to 1 TB SSD, up’d the RAM, and replaced the GPU at least once. But still, it was a 4-core system (8 threads) and it had performed admirably. The Intel NIC was needed because the built-in ASUS Realtek NIC was a piece of crap, only able to push about 90 MB/s. The Intel NIC was able to push 120 MB/s (close to the theoretical max for 1 Gigabit which is125 MB/s).
The thing that broke the camel’s back, however, was video. Specifically 4K video. I’ve been doing video edits and so forth in 1080p, but moving to 4K and the power of Premerier Pro (as opposed to iMovie) was just killing my system. 1080p was a challenge, and 4K madeit keel over.
I tend to get obsessive about new tech purchases. My first flat screen TV purchase in 2006 was the result of about a month of in-depth research. I pour over specs and reviews for everything from parachutes (btw, did you know I’m a skydiver?) to RAM. Eventually, here’s the system I settled on: Ryzen 7 3700x CPU (8 cores/16 threads, 3.6 GHz boost to 4.4 GHz)ASRock Steel
Legend: https://www.newegg.com/p/N82E16813157894?Item=N82E16813157894ASRock Radeon
5700XT: https://www.newegg.com/asrock-radeon-rx-5700-xt-rx-5700-xt-challenger-d-8g-oc/p/N82E16814930020?Item=N82E16814930020 32 GB of Corsair Vengence RAM https://www.newegg.com/corsair-32gb-288-pin-ddr4-sdram/p/N82E16820236454?Item=N82E168202364541 TB NVMe
M.2 https://www.amazon.com/gp/product/B07TBBB9BQ/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 Case: https://www.newegg.com/matte-white-black-nzxt-h-series-h510i-atx-mid-tower/p/N82E16811146320?Item=N82E16811146320Power
Supply: https://www.newegg.com/corsair-rm-series-rm850-cp-9020196-na-850w/p/N82E16817139248?Item=N82E16817139248 AMD came out of nowhere and launched Ryzen 3, which put ADM from a budget-has-been to a major contender in the desktop world. Plus, they were the first to come out with PCIe Gen 4.0, which allowed for each lane of PCIe to give you 2 GB/s of bandwidth. m.2 drives can connect to 4 lanes, giving a possible throughput of 8 GB/s of bandwidth. Compare that with SATA 3, at 600 MB/s, and that’s quite a difference. SATA is fine for spinning rust, but it’s clear NVMe is the only way to unlock SSD storage’s potential. When I built the system, I initially installed Linux (CentOS 7.6, to be exact) just to run a few benchmarks. I was primarily interested in the NVMe drive and the throughput I could expect. The drive advertises 5 GB/s reads and 4.3 GB/s writes. Using dd if=/dev/zero of=testfile and using various blocksizes and counts to write a 100 GB file, I was able to get about 2.8 GB/s writes. Not quite what the drive had promised in terms of writes, but much better than the 120. I was able to get about 3.2 GB/s reads. For various reasons (including that while Linux is a fantastic OS in lots of regards, it still sucks on the desktop, especially for my particular needs) I loaded up Windows 10. CrystalDiskMark is a good free benchmark and I was able to test my new NVMe drive there. I ran it, thinking I’d get the same results from Linux. Nope! I got pretty much what the drive promised. As a comparison, here’s how my old SATA SSD fared: About 10x performance. Here’s a couple of takeaways: PCIe 4 does matter for storage throughput. Would I actually notice in my day-to-day operations the difference between PCIe 3 and PCIe 4? Probably not. But I’m working with 4K video and some people are already working with 6K and even 8K video, that’s not too far downthe line for me.
SATA is dead for SSD storage. The new drives are more than capable of utterly overwhelming SATA 3 (600 MB/s, LOL). Right now, SATA is sufficient for HDDs, but as platters get bigger sequential reads willcontinue to climb.
I don’t doubt that Linux can do the same, it’s just my methodology failed me. The dd command from /dev/zero had never failed to be the best way to test write speeds for HDD and SATA SSDs, but now I need to find another method for Linux (or perhaps there is some type of bottleneck in Linux).TL;DR
New PCIe 4 NVMe SSDs are super fast and can be had for a relatively low amount of money ($180 USD for 1 TB). They’re insanely fast. I need a new way to benchmark Linux storage. Filed under Uncategorized FOR ESXI: REALTEK NICS ARE AWFUL AND DON’T USE THEM May 24, 2019 Leave a comment OK, this isn’t a really a controversial opinion. This is more as a guide for those who run into these problems when trying to setup their first whitebox/homelab systems for ESXi. So it goes something like this: You’ve got an old desktop, gaming rig, or workstation. You decide you’ll retire it to your home data center (or basement, or laundry room) as a hypervisor. ESXi by itself (no vSphere controller) is free, and here’s how to download and getthe license key.
For most desktop/workstation type of hardware, you can install ESXi from the general ESXi installer except for one aspect: Many of these types of systems use Realtek, Marvell, or other desktop/consumer grade NICs, and there’s not an ESXi driver for these. And for goodreasons: They suck.
So you have the choice: Try to use a special custom ISO installer with the Realtek?Marvell/etc. driver loaded, or buy a different NIC. In most of IT, there’s usually more than one right answer, and a heaping dose of “it depends”. However, for this particular question (Realtek or buy another NIC) there’s only right right answer: Buy another NIC. Realtek NICs suck. They don’t perform well, they’re a pain to work with for ESXi, so just buy a NIC. The other desktop NICs don’t fare much better. If it’s not recognized by ESXi, it’s a pretty goodbet it’s shit.
You can get a one or two port Intel Pro 1000 NIC on eBay for $20-30 USD. These NICs work great. I’ve even replaced the Realtek NIC on my Windows 10 Pro workstation and went from 700 Mbps to fully saturating a gigabit NIC for file transfers. (Make sure they’re Intel Server NICs, the Pro NICs, and not the desktop NICs.) For $20-30 additional, you can install ESXi on just about any desktop or workstation hardware with the standard ESXi installer. I’m sure there are edge cases, but for me desktop/workstation plus Intel Pro NIC has worked fine. Filed under Uncategorized CERTIFICATION EXAM QUESTIONS THAT I HATE March 12, 2019 Leave a comment In my 11 year career as an IT instructor, I’ve had to pass a lot of certification exams. In many cases not on the first try. Sometimes for fair reasons, and sometimes, it feels, for unfair reasons. Recently I had to take the venerable Cisco CCNA R&S exam again. For various reasons I’d allowed it to expire, and hadn’t taken many exams for a while. But recently I needed to re-certify with it which reminded me of the whole process. Having taken so many exams (50+ in the past 11 years) I’ve developed some _opinions_ on the style and content of exams. In particular, I’ve identified some types of questions I utterly loath for their lack of aptitude measurement, uselessness, and overall jackassery. Plus, a couple of styles that I like. This criticisms is for all certification exams, from various vendors, and not limited to even IT. TO CERTIFY, OR NOT TO CERTIFY The question of the usefulness of certification is not new. One one hand, you have a need to weed out the know-its from the know-it-nots, a way to effectively measure a person’s aptitude in a given subject. A certification exam, in its purest form, is meant to probe the knowledge of the applicant. On the other hand, you have an army of test-dumping dullards, passing exams and unable to explain even basic concepts. That results in a cat-and-mouse game between the exam creators and the dump sites. And mixed in, you have a barrage of badly formed questions that are more appropriate to your local pub’s trivia night than it is a professional aptitude measurement. So in this article I’m going to discuss the type of questions I despise. Not just because they’re hard, but because I can’t see how they accurately or fairly judge a person’s aptitude. _Note: I made all of these questions up. As far as I know, they do not appear on any certification exam from any vendor. This is not atest-dump. _
PEDANTIC TRIVIA
The story goes that Albert Einstein was once asked how many feet are in a mile. His response was this: _“I don’t know, why should I fill my brain with facts I can find in two minutes in any standardreference book?”_
I really relate to Einstein here (we’re practically twinsies). So many exam questions I’ve sat through were pure pedantic trivia. The knowledge of the answer had no bearing on the aptitude of theapplicant.
Here’s an example, similar to ones I recall on various exams: > _What is the order of ink cartridges in your printer? Choose one._>
> _A: Black, Magenta, Cyan, Yellow_>
> _B: Yellow, Cyan, Magenta, Black_>
> _C: Magenta, Cyan, Black, Yellow_ Assuming you have a printer with color cartridges, can you remember the order they go in? Do you care? Does it matter? Chances are there’s a diagram to tell you were to put them. Some facts are so obscure they’re not worth knowing. That’s why reference sources are there. I can even make the argument about certain details about regularly used aspects of your job. Take VRRP for example. For network administrators, VRRP and similar are a way to have two or more routers available to answer to a single IP address, increasing availability. This is a fundamental networking concept, one that any network administrator should know. VRRP uses a concept known as a vMAC. This is a MAC address that sits with the floating IP address, together making a virtual router that can move between physical routers. So far, everything about what I’ve described about VRRP (and much more that I haven’t) would be fair game for test questions. But a question that I think is useless is the following: > _The vMAC for VRRP is (where XX is the virtual router ID): _>
> _A: 00:01:5A:01:00:XX_>
> _B: 00:00:5A:01:00:XX_>
> _C: 00:01:5E:00:FF:XX_>
> _D: 00:00:5E:00:01:XX_ I’m willing to bet that if you ask 10 good CCIEs what the vMAC address of a VRRP is, none would be able to recite. Knowledge of this address has no bearing on your ability to administer a network. How VRRP works is important to understand, but this minutia is useless. I have two theories where these questions come from. Theory 1: I’ve written test questions (for chapter review, I don’t think I’ve written actual certification questions) and I know it’s difficult to come up with good questions. Test banks are often in the hundreds, and it can be a slog to make enough. Trivia questions are easy to come up with and easy to verify. Theory 2: Test dumpers. In the cat and mouse game between test writers and test dumpers, vendors might feel the need to up the difficulty level because pass rates get too high (which I think only hurts thehonest people).
EXACT COMMANDS
Another one I really despise is when a question asks you for the _exact_ command to do something. For example: > Which command will send the contents of one directory to a remote > server using SSH?>
> _A: tar -cvf – directory | ssh root@192.168.10.10 “cd > /home/user/; tar -xvf -” _>
> B: _tar -xvf – directory | ssh root@192.168.10.10 “cd > /home/user/; tar -xvf -” _>
> C: _tar -cvf – directory > ssh root@192.168.10.10 “cd > /home/user/; tar -cvf -” _>
> D: _ssh root@192.168.10.10 “cd /home/user/ tar -xvf -” > tar> -xvf directory_
For common tasks, such as deleting files, that’s probably fair game (though not terribly useful). Most CLIs (IOS, Bash, PowerShell) has tab completions, help, etc., so that any command syntax can be looked up. Complex pipes like the former are the kind I use with some regularity, but I often have to look it up. THE UNCLEAR QUESTIONS I see these in certification tests all the time. It’ll be a questionlike the following:
_What are some of the benefits of a pleasant, warm, sunny day? (ChooseThree)_
* _A: Vitamin D from sunlight_ * _B: Ability to have a picnic in a park_ * _C: No need for adverse weather clothing_ * _D: Generally improves most people’s disposition_ Look at those answers. You could make an argument for any of the four, though the question is looking for three. They’re all pretty correct. Reasonable people, even intelligent, experienced people, can disagree on that correct answer is.QUESTIONS I DO LIKE
I try not to complain about something if I don’t have something positive to contribute. So here’s my contribution: These are test questions that I think are more than fair. If I don’t know the answers to these types of questions, I deserve, in every sense of fairness, to get the question wrong.SCENARIO QUESTIONS
A scenario question is something like this: “Given X, what wouldhappen”.
_For example, if a BDPU was received on portfast enabled interface, what would happen? _Or
_If a host with an IP netmask combo of 192.168.1.10/24 was to try to communicate with a host configured on the same Layer 2 segment with an IP address of 192.168.1.119/25, would they be able to communicate? _ I like those types of questions because they test your understanding of how things work. That’s far more important for determiningcompetency I think.
There are some network basics, that might seem like trivia, but knowing would be important to know. For example: > What is the order of a TCP handshake?>
> A: ACK, SYN/ACK, SYN>
> B: SYN, SYN/ACK, ACK>
> C: SYN, ACK/SYN, SYN>
> D: ACK, ACK/SYN, SYN This question is fundamental to the operations of networks, and I would hope any respectable network engineer would know this. This would be important for TCP dump analysis, and other fundamentaltroubleshooting.
CONCLUSION
If you write test questions, ask yourself: _Would the best people doing what this question tests get this answer right? Is it overly pedantic? Is there a clear answer? _ This was mostly written as a frustration piece. But I think I’m not alone in this frustration. Filed under Uncategorized A DISCUSSION ON STORAGE OVERHEAD January 27, 2019 1 Comment Let’s talk about transmission overhead. For various types of communications protocols, ranging from Ethernet to Fibre Channel to SATA to PCIe, there’s typically additional bits that are transmitted to help with error correction, error detection, and/or clock sync. These additional bits eat up some of the bandwidth, and is referred to generally as just “the overhead”. For 1 Gigabit Ethernet and 8 Gigabit Fibre Channel as well as SATA I, II, and III, they use 8/10 overhead. Which means for every eight bits of data, an additional two bits are sent. The difference is who pays for those extra bits. With Ethernet, Ethernet pays. With Fibre Channel and SATA, the user pays. 1 Gigabit Ethernet has a raw transmit rate of 1 gigabit per second. However, the actual transmission rate (baud, the rate at which raw 1s and 0s are transmitted) for Gigabit Ethernet is 1.25 gigabaud. This is to make up for the 8/10 overhead. SATA and Fibre Channel, however, do not up the _baud_ rate to accommodate for the 8/10 overhead. As such, even though 1,000 Gigabit / 8 bits per byte = 125 MB/s, Gigabit Fibre Channel only provides 100 MB/s. 25 MB/s is eaten up by the extra 2 bits in the encoding. The same is true for SATA. SATA 3 is capable of transmitting at 6 Gigabits per second, which is 750 MB/s. However, 150 MB/s of that is eaten up by the extra 2 bits, so SATA III can transmit 600 MB/s instead.PAM 4
There’s a new type of raw data transmission hitting the networking world called PAM 4. Right now it’s used in 400 Gigabit Ethernet. 400 Gigabit Ethernet is 4 channels of 50 Gigabit links. You’ll probably notice the math on that doesn’t check out: 4 x 50 = 200, not 400. That’s where PAM 4 comes in: The single rate change is still 50 gigabaud, but instead of the signal switching between two possible values (0, 1), it switches between 4 possible values (0, 1, 2, 3). Thus, each clock cycle can represent 2 bits of data in stead of 1 bit of data, doubling the transmission rate. HIGHER LEVEL PROTOCOL OVERHEAD For networking storage on Ethernet, there’s also additional overhead for IP, TCP/UDP, and possibly others (VXLAN for example). In my _next_ article, I’ll talk about why they don’t really matterthat much.
Filed under Uncategorized A PRIMER FOR HOME NAS STORAGE SPEED UNITS AND ABBREVIATIONS January 26, 2019 Leave a comment One of the most common mistakes/confusion I see with regard to storage is how speed is measured. In tech, there’s some cultural conventions to which units speeds arediscussed in.
* In the networking world, we measure _bits per second_ * In the storage and server world, we measure speed in _bytes persecond_
Of course they both say the same thing, just in different units. You could measure bytes per second in the networking world and bits per second in the server/storage world, but it’s not the “native” method and could add to confusion. For NAS, we have a bit of a conundrum in that we’re talking about both worlds. So it’s important to communicate effectively _which_ method you’re using to measure speed: bits of bytes. Generally speaking, if you want to talk about _Bytes_, you capitalize the B. If you want to talk about bits, the b is lower case. I.e. 100 MB/s (100 MegaBYTES per second) and 100 Mbit or Mb (100 MegaBIT persecond).
This is important, because there a 8 bits in a byte, the difference in speed is pretty stark depending on if you’re talking about bits per second or bytes per second. Examples: * 200 Mb/s is written to mean 200 MegaBITS per second * 200 MB/s is written to mean 200 MegaBYTES per second Again, the speed difference is pretty stark: * 200 Mb/s (Megabits per second, about 1/5th of the total rate available on Gigabit Ethernet) = 25 Megabytes per second * 200 MB/s (Megabytes per second, almost double what a Gigabit Ethernet links could send) = 1.6 Gigabits/second 200 Mb/s easily fits in a Gigabit Ethernet link. 200 MB/s is more than a Gigabit Ethernet link could handle.ABBREVIATIONS
It’s generally acceptable to write bits per second as Xb, Xbit, Xbit/s, and Xbps, where X is the multiplier prefix (Mega, Giga, Tera,etc.)
The following are examples of 1.21 Gigabits per second :* 1.21 Gbps
* 1.21 Gb/s
* 1.21 Gbit/s
It’s generally acceptable to write bytes per second as XB, XByte, XByte/s, and XBps, where X is the multipler (Mega, Giga, Tera, etc.) The following are examples of 1.21 Gigabytes per second: * 1.21 GBps (less common)* 1.21 GB/s
* 1.21 GByte/s
A Gigabit Ethernet interface can theoretically handle 125 MB/s (1,000 mbit / 8 bits per byte = 125). A 10 Gigabit Ethernet interface. Depending on your NIC, horsepower, and systems, you may or not be able to reach that. But that’s the theoretical limit for GigabitEthernet.
10 Gigabit Ethernet (10GE) can theoretically handle 1250 MB/s (10,000 mbit / 8 bits per byte).BINARY MULTIPLIERS
There’s also KiB (Kibi Byte) and Kib (Kibibit), where kibi is a 1024 multiplier, and not 1,000. GiB (GibiByte) and TiB (TibiByte) are 10242 and 10243, respectively. The idea is to be native to the binary numbers, rather than multiplesof 10 (decimal).
We don’t tend to use those measurements in network or storage transmit/receive rates, but it’s showing up more and more in raw storage measurements.OVERHEAD
SATA I, II, and III are 1.5, 3, and 6 Gigabits/second respectively. They push 150, 300, and 600 MB/s respectively. You’ll probably note that math doesn’t check out: 6 Gigabits/second divided by 8 bits in a byte is 750 MB/s, not 600 MB/s, so where did the extra 150 MB/s go? I’ll cover that in the next article. Read more of this post Filed under Uncategorized MICROSOFT STORAGE SPACES IS HOT GARBAGE FOR PARITY STORAGE December 17, 2018 15 Comments I love parity storage. Whether it’s traditional RAID 5/6, erasure coding, raidz/raid2z, whatever. It gives you redundancy on your data without requiring double the drives that mirroring or mirroring+stripping would require. The drawback is write performance is not as good as mirroring+stripping, but for my purposes (lots of video files, cold storage, etc.) parity is perfect. In my primary storage array, I use double redundancy on my parity, so effectively N+2. I can lose any 2 drives without losing any data. I had a simple Storage Spaces mirror on my Windows 10 Pro desktop which consisted of (2) 5 TB drives using ReFS. This had four problems: * It was getting close to full * The drives were getting old * ReFS isn’t support anymore on Windows 10 Pro (need Windows 10Workstation)
* Dropbox (which I use extensively) is dropping support for ReFS-based file systems. ReFS had some nice features such as checksumming (though for data checksumming, you had to turn it on),
but given the type of data I store on it, the checksumming isn’t that important (longer-lived data is stored either on Dropbox and/or my ZFS array). I do require Dropbox, so back to NTFS it is. I deal with a lot of large files (video, cold-storage VM virtual disks, ISOs, etc.) and parity storage is great for that. For boot volumes, OS, applications, and other latency-sensitive operations, it’s SSD or NVMe all the way. But the bulk of my storage requirements is, well, bulk storage. I had a few more drives from the Best Buy Easystore sales (8 TB drive, related to the WD Reds, for about $129 during their most recent sale) so I decided to use three of them and create myself a RAID 5 array (I know there are objections to RAID 5 these days in favor of RAID 6, while I agree with some of them, they’re not applicable to this workload, so RAID 5 is fine). So I’ve got 3 WD Easystore shucked drives . Cool. I’ll create aRAID 5 array.
Shit. Notice how the RAID-5 section is grayed out? Yeah, somewhere along the line Windows removed the ability to create RAID 5 volumes in their non-server operating systems. Instead Microsoft’s solution is to use the newer Storage Spaces. OK, fine. I’ll use storage spaces. There’s a parity option, so like RAID 5, I can do N+1 (or like RAID6, N+2, etc.).
I set up a parity storage space (the UI is pretty easy) and gave it a quick test. At first, it started sending at 270 MB/s, then it dropped off a cliff to… 32 MB/s. That’s it. 32 MB/s a second. What. The. Eff. I’ve got SD cards that can write faster. My guess is that some OS caching was allowing it to copy at 270 MB/s (the hard drives aren’t capable of 270 MB/s). But the hard drives ARE capable of far more than 32 MB/s. Tom’s Hardware found the Reds capable of 200 MB/s sequential writes.
I was able to get 180 MB/s with some file copies on a raw NTFS formatted drive, which is inline with Tom’s Hardware’s conclusion. Now, I don’t need a whole lot of write performance for this volume. And I pretty much only need it for occasional sequential reads and writes. But 32 MB/s is not enough. I know what some of you are thinking. “Well Duh, RAID 5/parity is slower for writes because of the XOR calculations”. I know from experience on similar (and probably slower) drives, that RAID 5 is not that slow, even on spinning disks. The XOR calculations are barely a blip in the processor for even halfway modern systems. I’ve got a Linux MD RAID system, with 5 drives and I can get ~400 MB/s of writes (from a simple dd write test). While it’s true RAID 5 writes are slower than say, RAID 10, they’re not that slow. I set up a RAID 5 array on a Windows Server 2016 machine (more on that later) using the _exact same drives_ it was able to push 113 MB/s. It might have been able to do more, but it was limited by the bottleneck of the Ethernet connection (about 125 MB/s) and the built-in Dell NIC. I didn’t have an SSD to install Windows Server 2016 on and had to a use a HDD that was slower than the drives the RAID 5 array was built with so that’s the best I could do. Still, even if that was the maximum, I’ll be perfectly happy with 113 MB/s for sequential writes. So here’s where I got crafty. The reason I had a Windows 2016 server was that I thought if I created a RAID 5 volume in Windows 2016 (which you can) I could simply _import_ the volume into Windows 10 Pro. Unfortunately, after a few attempts, I determined that that won’twork.
The volume shows failed and the individual drives show failed as well. So now I’m stuck with a couple of options:* Fake RAID
* Drive mirroring
* Parity but suck it up and deal with 32 MB/s * Parity and buy a pair of small SSDs to act as cache to speed upwrites
* By a Hardware RAID CardFAKE HARDWARE RAID
Early on in my IT career, I’d been fooled by fake RAID. Fake RAID is the feature that many motherboards and inexpensive SATA cards offer: You can setup RAID (0, 1, 5 typically) in the motherboard BIOS. But here’s the thing: It’s not a dedicated RAID card. The RAID operations are done by the general CPU. It has all the disadvantages of hardware RAID (difficult to troubleshoot, more fragile configurations, very difficult to migrate) and none of the advantages (hardware RAID offloads operations to a dedicated CPU on the RAID card, which fake RAID doesn’t have). For me, it’s more important to have portability of the drives (just pull disks out of one system and into another). So fake RAID is out.DRIVE MIRRORING
Having tested drive mirroring performance, it’s definitely a betterperforming option.
PARITY WITH SUCKY PERFORMANCE I could just suck it up and deal with 32 MB/s. But I’m not going to. I don’t need SSD/NVMe speeds, but I need something faster than 32 MB/s. I’m often dealing with multi-gigabit files, and 32 MB/s is a significant hindrance to that. PARITY WITH SSD CACHE About $50 would get me two 120 GB SSDs. As long as I wasn’t doing a massive copy beyond 120 GBs of data, I should get great performance. For my given workload of bulk storage (infrequent reads/writes, mostly sequential in nature) this should be fine. The initial copy of my old mirrored array is going to take a while, but that’s OK. The trick with an SSD cache is that you have to use PowerShell in order to configure it. The Windows 10 GUI doesn’t allow it. After some fiddling, I was able to get a Storage Space going with SSDcache.
And… the performance was worse than with the drives by itself. Testing the drives by themselves, I found the that the SSDs had worse sequential performance than the spinning rust. I’d assumed the SSDs would do better, a silly assumption now that I think about it. At least I’m out only $50, and I can probably re-purpose them forsomething else.
The performance for random I/O is probably better, but that’s not what my workload is on these drives. My primary need is sequential performance for this volume. BUY A HARDWARE RAID CARD I don’t like hardware RAID cards. They’re expensive, the software to manage them tends to be really awful, and it make portability of drives a problem. With software RAID, I can pull drives out of one system and put them into another, and voila, the volume is there. That can be done with a hardware RAID card, but it’s trickier. The performance benefit that they provide is just about gone too, given how fast modern CPUs are and how many cores they have, compared to the relatively slow CPUs on hardware RAID cards (typically less than a GHz, and only one or two cores).CONCLUSION
So in the end, I’m going with a mirrored pair of 8 TB drives, and I have two more drives I can add when I want to bring the volume to 16TB.
THOUGHTS ON WHY STORAGE SPACES PARITY IS SUCH HOT FUCKING GARBAGE There’s a pervasive thought in IT that parity storage is very slow unless you have a dedicated RAID card. While probably true at one time, much like the jumbo frame myth, it’s no longer true anymore. A halfway modern CPU is capable of dozens of Gigabytes per second of RAID 5/6 or whatever parity/erasure coding. If you’re just doing a couple hundred megabytes per second, it’s barely a blip in the CPUs. It’s the reason huge honking storage arrays (EMC, Dell, NetApp, VMware VSAN etc.) don’t do RAID cards. They just (for the most part) throw x86 cores at it through either scale-up or scale-outcontrollers.
So why does Storage Space parity suck so bad? I’m not sure. It’s got to be an implementation problem. It’s definitely not a CPU bottleneck. It’s a shame too, because it’s very easy to manage and more flexible than traditional software RAID.(WAY)TL;DR
Tried parity in storage spaces. It sucked bigtime. Tried other shit, didn’t work. Just went with mirrored. Filed under Uncategorized ZFS ON LINUX WITH ENCRYPTION PART 2: THE COMPILING December 17, 2017 3 Comments _First off: Warning. I don’t know what the stability of this feature is. It’s been in the code for a couple of months, it hasn’t been widely used. I’ve been testing it, and so far it’s worked asexpected. _
In exploring native encryption, I attempted to get it on Linux/ZFS using the instruction on this site: https://blog.heckel.xyz/2017/01/08/zfs-encryption-openzfs-zfs-on-linux/. While I’m sure they worked at the time, the code in the referenced non-standard repos has changed and I couldn’t get anything tocompile correctly.
After trying for about a day, I realized (later than I care to admit) that I should have just tried the standard repos. They worked like a charm. The instructions below compiled and successfully installed ZFS on Linux with dataset encryption on both Ubuntu 17.10 and CentOS 7.4 in the November/December 2017 time frame. COMPILING ZFS WITH NATIVE ENCRYPTION The first step is to make sure a development environment is installed on your Linux system. Make sure you have compiler packages, etc. installed. Here’s a few packages for CentOS you’ll need (you’ll need similar packages/libraries for whatever platform you run).* openssl-devel
* attr, libattr-devel* libblkid-devel
* zlib-devel
* libuuid-devel
The builds were pretty good at telling you what packages you needed if they were missing, so of course install any that are requested. You’ll need to build the SPL code and the ZFS code. First, build the SPL code. git clone https://github.com/zfsonlinux/splcd spl
./autogen
./configure
make
make install
Then the ZFS code:
git clone https://github.com/zfsonlinux/zfscd zfs
./autogen
./configure --prefix=/usr # <-- This puts the binaries in /usr/sbin instead of /usr/local/sbinmake
make install
If you try the zfs command right away, you’ll probably get something similar to the following: /sbin/zfs: error while loading shared libraries: libnvpair.so.1: cannot open shared object file: No such file or directory Running ldconfig usually fixes that. You might need to modprobe zfs to get the modules loaded, especially if you end up rebooting. There’s of course ways to auto-load the modules depending on your distribution.CREATING THE ZPOOL
zpool create -o ashift=12 storage raidz2 /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg The -o ashift=12 is important if you have 4K sector drives, which these 8 TB WD Reds are. If you don’t throw that option in, your performance will suffer, big-time. I found my pool performed about 25% of what it did when ashift=12 was selected. I was doing copy tests with Samba and getting only 25-30 MB/s. Once I destroyed the zpool and used ashift=12 for a new zpool on the same drives, I was able to get ~120 MB/s, which is the practical limit for a 1 Gigabit link (1,000 Gbit / 8 = 125 MB/s). Local copies were faster. Figure this out ahead of time, because to set the ashift you have to do zpool destroy, which does what it sounds like it does: Destroys the pool (and data). The zpool will be called “storage” (yes, original) so of course use whatever name you prefer. raidz2 uses a double-parity system, so out of 6 drives, I would get a pool with the space of 4 of them(roughly 32 TBs).
The rest are the devices themselves. You don’t need to partition the drives, ZFS does it automatically. Encryption is done on a dataset by dataset basis, which is nice to be able to have some storage be encrypted and other parts not. To create an encrypted dataset, first enable the feature in the zpool. zpool set feature@encryption=enabled storage Then create a new dataset under the storage zpool using a passphrase (you can also use a keyfile, but I’m opting for a passphrase): zfs create -o encryption=on -o keylocation=prompt -o keyformat=passphrase storage/encrypted Anything you put in /storage/encrypted/ will now be encrypted at rest. When the system comes up, the zpool could be automatically imported (or you have to import it manually) but the /storage/encrypted/ dataset won’t be automatically added. # zpool import storage # zfs mount storage/encrypted -l # Enter passphrase for 'storage/encrypted': Once you enter the passphrase, the dataset is mounted. Filed under Uncategorized← Older posts
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