Category Archives: NIC Teaming

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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Design Considerations For Converged Networking On A Budget With Switch Independent Teaming In Windows Server 2012 Hyper-V

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Last Friday I was working on some Windows Server 2012 Hyper-V networking designs and investigating the benefits & drawbacks of each. Some other fellow MVPs were also working on designs in that area and some interesting questions & answers came up (thank you Hans Vredevoort for starting the discussion!)

You might have read that for low cost, high value 10Gbps networks solutions I find the switch independent scenarios very interesting as they keep complexity and costs low while optimizing value & flexibility in many scenarios. Talk about great ROI!

So now let’s apply this scenario to one of my (current) favorite converged networking designs for Windows Server 2012 Hyper-V. Two dual NIC LBFO teams. One to be used for virtual machine traffic and one for other network traffic such as Cluster/CSV/Management/Backup traffic, you could even add storage traffic to that. But for this particular argument that was provided by Fiber Channel HBAs. Also with teaming we forego RDMA/SR-IOV.

For the VM traffic the decision is rather easy. We go for Switch Independent with Hyper-V Port mode. Look at Windows Server 2012 NIC Teaming (LBFO) Deployment and Management to read why. The exceptions mentioned there do not come into play here and we are getting great virtual machine density this way. With lesser density 2-4 teamed 1Gbps ports will also do.

But what about the team we use for the other network traffic. Do we use Address hash or Hyper-V port mode. Or better put, do we use native teaming with tNICs as shown below where we can use DCB or Windows QoS?

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Well one drawback here with Address Hash is that only one member will be used for incoming traffic with a switch independent setup. Qos with DCB and policies isn’t that easy for a system admin and the hardware is more expensive.

So could we use a virtual switch here as well with QoS defined on the Hyper-V switch?

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Well as it turns out in this scenario we might be better off using a Hyper-V Switch with Hyper-V Port mode on this Switch independent team as well. This reaps some real nice benefits compared to using a native NIC team with address hash mode:

  • You have a nice load distribution of the different vNIC’s send/receive traffic over a single member of the NIC team per VM. This way we don’t get into a scenario where we only use one NIC of the team for incoming traffic. The result is a better balance between incoming and outgoing traffic as long an none of those exceeds the capability of one of the team members.
  • Easy to define QoS via the Hyper-V Switch even when you don’t have network gear that supports QoS via DCB etc.
  • Simplicity of switch configuration (complexity can be an enemy of high availability & your budget).
  • Compared to a single Team of dual 10Gbps ports you can get a lot higher number of VM density even they have rather intensive network traffic and the non VM traffic gets a lots of bandwidth as well.
  • Works with the cheaper line of 10Gbps switches
  • Great TCO & ROI

With a dual 10Gbps team you’re ready to roll. All software defined. Making the switches just easy to use providers of connectivity. For smaller environments this is all that’s needed. More complex configurations in the larger networks might be needed high up the stack but for the Hyper-V / cloud admin things can stay very easy and under their control. The network guys need only deal with their realm of responsibility and not deal with the demands for virtualization administration directly.

I’m not saying DCB, LACP, Switch Dependent is bad, far from. But the cost and complexity scares some people while they might not even need. With the concept above they could benefit tremendously from moving to 10Gbps in a really cheap and easy fashion. That’s hard (and silly) to ignore. Don’t over engineer it, don’t IBM it and don’t go for a server rack phD in complex configurations. Don’t think you need to use DCB, SR-IOV, etc. in every environment just because you can or because you want to look awesome. Unless you have a real need for the benefits those offer you can get simplicity, performance, redundancy and QoS in a very cost effective way. What’s not to like. If you worry about LACP etc. consider this, Switch independent mode allows for nearly no service down time firmware upgrades compared to stacking. It’s been working very well for us and avoids the expense & complexity of vPC, VLT and the likes of that. Life is good.

Windows Server 2012 NIC Teaming Mode “Independent” Offers Great Value

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There, I said it. In switching, just like in real life, being independent often beats the alternatives. In switching that would mean stacking. Windows Server 2012 NIC teaming in Independent mode, active-active mode makes this possible. And if you do want or need stacking for link aggregation (i.e. more bandwidth) you might go the extra mile and opt for  vPC (Virtual Port Channel a la CISCO) or VTL (Virtual Link Trunking a la Force10 – DELL).

What, have you gone nuts? Nope. Windows Server 2012 NIC teaming gives us great redundancy with even cheaper 10Gbps switches.

What I hate about stacking is that during a firmware upgrade they go down, no redundancy there. Also on the cheaper switches it often costs a lot of 10Gbps ports (no dedicated stacking ports). The only way to work around this is by designing your infrastructure so you can evacuate the nodes in that rack so when the stack is upgraded it doesn’t affect the services. That’s nice if you can do this but also rather labor intensive. If you can’t evacuate a rack (which has effectively become your “unit of upgrade”) and you can’t afford the vPort of VTL kind of redundant switch configuration you might be better of running your 10Gbps switches independently and leverage Windows Server 2012 NIC teaming in a switch independent mode in active active. The only reason no to so would be the need for bandwidth aggregation in all possible scenarios that only LACP/Static Teaming can provide but in that case I really prefer vPC or VLT.

Independent 10Gbps Switches

Benefits:

  • Cheaper 10Gbps switches
  • No potential loss of 10Gbps ports for stacking
  • Switch redundancy in all scenarios if clusters networking set up correctly
  • Switch configuration is very simple

Drawbacks:

  • You won’t get > 10 Gbps aggregated bandwidth in any possible NIC teaming scenario

Stacked 10Gbps Switches

Benefits:

  • Stacking is available with cheaper 10Gbps switches (often a an 10Gbps port cost)
  • Switch redundancy (but not during firmware upgrades)
  • Get 20Gbps aggregated bandwidth in any scenario

Drawbacks:

  • Potential loss of 10Gbps ports
  • Firmware upgrades bring down the stack
  • Potentially more ‘”complex” switch configuration

vPC or VLT 10Gbps Switches

Benefits:

  • 100% Switch redundancy
  • Get > 10Gbps aggregated bandwidth in any possible NIC team scenario

Drawbacks:

  • More expensive switches
  • More ‘”complex” switch configuration

So all in all, if you come to the conclusion that 10Gbps is a big pipe that will serve your needs and aggregation of those via teaming is not needed you might be better off with cheaper 10Gbps leverage Windows Server 2012 NIC teaming in a switch independent mode in active active configuration. You optimize 10Gbps port count as well. It’s cheap, it reduces complexity and it doesn’t stop you from leveraging Multichannel/RDMA.

So right now I’m either in favor of switch independent 10Gbps networking or I go full out for a vPC (Virtual Port Channel a la CISCO) or VTL (Virtual Link Trunking a la Force10 – DELL) like setup and forgo stacking all together. As said if you’re willing/capable of evacuating all the nodes on a stack/rack you can work around the drawback. The colors in the racks indicate the same clusters. That’s not always possible and while it sounds like a great idea, I’m not convinced.

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When the shit hits the fan … you need as little to worry about as possible. And yes I know firmware upgrades are supposed to be easy and planned events. But then there is reality and sometimes it bites, especially when you cannot evacuate the workload until you’re resolved a networking issue with a firmware upgrade Confused smile Choose your poison wisely.