Category Archives: Networking

Verifying SMB 3.0 Multichannel/RDMA Is Working In Windows Server 2012 (R2)

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So you have spend some money on RDMA cards (RoCE in this example), spent even more money on 10Gbps Switches with DCB capabilities and last but not least you have struggled for many hours to get PFC, ETS, … configured. So now you’d like to see that your hard work has paid of, you want to see that RDMA power that SMB 3.0 leverages in action. How?

You could just copy files and look at the speed but when you have sufficient bandwidth and the limiting factor is in disk IO for example how would you know? Well let’s have a look below.

You can take a look at performance monitor for RDMA specific counters like “RDMA Activity” and “SMB Direct Connection”.image

Whilst copying six 3.4GB ISO files over the RDMA connection we see a speed of 1.05 GB/s. Not to shabby.  But hay nothing a good 10Gbps with TCP/IP can handle under the right conditions.image

It’s the RDMA counters in Performance Monitor that show us the traffic that going via SMB Direct.image

Another give away that RDMA is in play comes from Task Manager, Performance counters for the RDMA NIC => 1.3Mbps send traffic can’t possibly give us 1.05GB/s in copy speed magically Smile

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When you run netstat –xan (instead of the usual –an) you get to see the RDMA connection. The mode is “Kernel” instead of the usual “TCP” or “UDP” with –an showing the TCP/IP connections/Listerners.

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If you want to go all geeky there is an event log where you look at RDMA events amongst others. Jose Baretto discusses this in Deploying Windows Server 2012 with SMB Direct (SMB over RDMA) and the Mellanox ConnectX-3 using 10GbE/40GbE RoCE – Step by Step with instructions how to use it. You’ll need to go to Event Viewer.On the menu, select “View” then “Show Analytic and Debug Logs”
Expand the tree on the left: Applications and Services Log, Microsoft, Windows, SMB Client, ObjectStateDiagnostic. On the “Actions” pane on the right, select “Enable Log”
You then run your RDMA work. And then disable the log to view the events. Some filtering & PowerShell might come in handy to comb through them.image

Still Need To Optimizing Power Settings On DELL 12th Generation Servers For Lightning Fast Hyper-V Live Migrations?

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Do you remember my blog from 2011 on optimizing some system settings to get way better Live Migration performance with 10Gbps NICs?  It’s over here Optimizing Live Migrations with a 10Gbps Network in a Hyper-V Cluster. This advice still holds true, but the power optimization settings & interaction between DELL Generation 12 Server and with Windows Server 2012 has improved significantly. Where with Windows Server 2008 R2 we could hardly get above 16% bandwidth consumption out of the box with Live Migration over a 10Gbps NIC today this just works fine.

Don’t believe me?image You do now? A cool Winking smile

For overall peak system performance you might want to adjust your Windows configuration settings to run the High Performance preferred power plan, if that’s needed.image

You might do no longer need to dive into the BIOS. Of cause if you have issues because your hardware isn’t that intelligent and/or are still running Windows 2008 R2 you do want to there. As when it comes to speed we want it all and we want it now Smile and than you still want to dive into the BIOS and tweak it even on the DELL 12th Generation hardware. Test & confirm I’d say but you should notice a difference, all be it smaller than with Windows Server 2008 R2.

Well let’s revisit this again as we are now no longer working with Generation 10 or 11 servers with an “aged” BIOS. Now we have decommissioned the Generation 10 server,  upgrade the BIOS of our Generation 11 Servers and acquired Generation 12 servers. We also no use UEFI for our Hyper-V host installations. The time has come to become familiar with those and the benefits they bring. It also future proofs our host installations.

So where and how do I change the power configuration settings now? Let’s walk through one together. Reboot your server and during the boot cycle hit F2 to enter System Setup.image

Select System BIOSimage

Click on System Profile Settingsimage

The settings you want to adapt are:

  • CPU Power Management should be on Maximum Performance
  • Setting Memory Frequency to “Maximum Performance”
  • C1E states should be disabled
  • C states should be disabled

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That’s it. The below configuration has optimized your power settings on a DELL Generation 12 server like the R720.image

When don, click “Back” and than Finish. A warning will pop up and you need to confirm you want to safe your changes. Click “Yes” if you indeed want to do this.image

You’ll get a nice confirmation that your settings have been saved. Click “OK” and then click Finish.image

Confirm that you want to exit and reboot by clicking yes and voila, when the server comes back on it will be running a full speed at the cost of more power consumption, extra generated heat and cooling.image

Remember, if you don’t need to run at full power, don’t. And if you consider using  Dynamic Optimization and Power Optimization in System Center Virtual Machine Manager 2012. Save a penguin!

SMB Direct RoCE Does Not Work Without DCB/PFC

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Introduction

SMB Direct RoCE Does Not Work Without DCB/PFC. “Yes”, you say, “we know, this is well documented. Thank you.” but before you sign of hear me out.

Recently I plugged to RoCE cards into some test servers and linked them to a couple of 10Gbps switches. I did some quick large file copy testing and to my big surprise RDMA kicked in with stellar performance even before I had installed the DCB feature, let alone configure it. So what’s the deal here. Does it work without DCB? Does the card fail back to iWarp? Highly unlikely. I was expecting it to fall back to plain vanilla 10Gbps and not being used at all but it was. A short shout out to Jose Barreto to discuss this helped clarify this.

DCB/PFC is a requirement RoCE

The more busy the network gets the faster the performance will drop. Now in our test scenario we had two servers  for a total of 4 RoCE ports on the network consisting of a beefy 48 port 10Gbps switches. So we didn’t see the negative results of this here.

DCB (Data Center Bridging) and Priority Flow Control are considered a requirement for any kind of RoCE deployment. RDMA with RoCE operates at the Ethernet layer. That means there is no overhead from TCP/IP, which is great for performance. This is the reason you want to use RDMA actually. It also means it’s left on it’s own to deal with Ethernet-level collisions and errors. For that it needs DCB/PFC other wise you’ll run into performance issues due to a ton of retries at the higher network layers.

The reason that iWarp doesn’t require DCB/PCF is that it works at the TCP/IP level also offloaded by using a TCP/IP stack on the NIC instead of the OS. So errors are handled by TCP/IP at a cost: iWarp results in the same benefits as RoCE but it doesn’t scale that well. Not that iWarp performance is lousy, far form! Mind you, for bandwidth management reasons,you’d be better of using DCB or some form of QoS as well.

Conclusion

So no, not configuring  DCB on your servers and the switches isn’t an option, but apparently it isn’t blocked either so beware of this. It might appear to be working fine but it’s a bad idea. Also don’t think it defaults back to iWarp mode, it doesn’t, as one card does one thing not both. There is no shortcut. RoCE RDMA does not work error free out of the box so you do have the install the DCB feature and configure it together with the switches.

Using RAMDisk To Test Windows Server 2012 Network Performance

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I’m testing & playing different Windows Server 2012 & Hyper-V networking scenarios with 10Gbps, Multichannel, RDAM, Converged networking etc. Partially this is to find out what works best for us in regards to speed, reliability, complexity, supportability and cost.

Basically you have for basic resources in IT around which the eternal struggle for the prefect balance finds place. These are:

  • CPU
  • Memory
  • Networking
  • Storage

We need both the correct balance in capabilities, capacities and speed for these in well designed system. For many years now, but especially the last 2 years it very save to say that, while the sky is the limit, it’s become ever easier and cheaper to get what we need when it comes to CPU, Memory. These have become very powerful, fast and affordable relative to the entire cost of a solution.

Networking in the 10Gbps era is also showing it’s potential in quantity (bandwidth), speed (latency) and cost (well it’s getting there) without reducing the CPU or memory to trash thanks to a bunch of modern off load technologies. And basically in this case it’s these qualities we want to put to the test.

The most trouble some resource has been storage and it has been for quite a while. While SSD do wonders for many applications the balance between speed, capacity & cost isn’t that sweet as for our other resources.

In some environments were I’m active they have a need for both capacity and IOPS and as such they are in luck as next to caching a lot of spindles still equate to more IOPS. For testing the boundaries of one resource one needs to make sure non of the others hit theirs. That’s not easy as for performance testing can’t always have a truck load of spindles on a modern high speed SAN available.

RAMDisk to ease the IOPS bottleneck

To see how well the 10Gbps cards with and without Teaming, Multichannel, RDMA are behaving and what these configuration are capable of I wanted to take as much of the disk IOPS bottle neck out of the equation as possible. Apart from buying a Violin system capable of doing +1 million IOPS, which isn’t going to happen for some lab work, you can perhaps get the best possible IOPS by combining some local SSD and RAMDisk. RAMDisk is spare memory used as a virtual disk. It’s very fast and cost effective per IOPS. But capacity wise it’s not the worlds best, let alone most cost effective solution.

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I’m using free RAMDisk software provided by StarWind. I chose this as they allow for large sized RAMDisks. I’m using the ones of 54GB right now to speed test copying fixed sized VHDX files. It install flawlessly on Windows Server 2012 and it hasn’t caused me any issues. Throw in some SSDs on the servers for where you need persistence and you’re in business for some very nice lab work.

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You also need to be aware it doesn’t persist data when you reboot the system or lose power. This is not an issue if all we are doing is speed testing as we don’t care. Otherwise you’ll need to find a workaround and realize those ‘”flush the data to persistent storage” isn’t full proof or super fast, the SSDs do help here.

You have to register but the good news is that they don’t spam you to death at all, which I find cool. As said the tool is free, works with Windows Server 2012 and allows for larger RAMDisks where other free ones are often way to limited in size.

It has allowed me to do some really nice testing. Perhaps you want to check this out as well. WARNING: The below picture is a lab setup … I’m not a magician and it’s not the kind of IOPS I have all over the datacenters with 4 Cheapo SATA disks I touched my special magic pixie dust.

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With #WinServ 2012 storage costs/performance/capacity are the only thing limiting you http://twitter.yfrog.com/mnuo9fp #SMB3.0 #Multichannel

Some quick tests with a 52GB NTFS RAMDisk formatted with a 64K NTFS Allocation unit size.

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I also tested with another free tool from SoftPerfect ® RAM Disk FREE. It performs well but I don’t get to see the RAMDisk in the Windows Disk Management GUI, at least not on Windows Server 2012. I have not tested with W2K8R2.

NTFS Allocation unit size 4K NTFS Allocation unit size 64K
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