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Hyper-V virtual controller for I/O intensive drives? RRS feed

  • Question

  • Good morning,

    In the world of VMWare where I'm far more comfortable, it's always been best practice to run I/O intensive applications (Read: SQL, SQL, SQL, and maybe large file servers w/Windows Dedupe enabled) with a dedicated virtual storage controller (namely a pvscsi) for the VVOL/VMDKs

    I can't find any documentation anywhere, from anyone on what the Hyper-V synthetic/virtual SCSI Controller limits and/or best practices are for such workloads, let alone where the tipping point is to adding another one.

    Thoughts or links to material I could go through?  I feel like I've exhausted Google and Microsoft's material.

    Wednesday, May 20, 2020 4:13 PM

All replies

  • Some info and recommendations here.

    https://docs.microsoft.com/en-us/windows-server/virtualization/hyper-v/plan/plan-hyper-v-scalability-in-windows-server

    https://docs.microsoft.com/en-us/windows-server/administration/performance-tuning/role/hyper-v-server/storage-io-performance

     

     



    Regards, Dave Patrick ....
    Microsoft Certified Professional
    Microsoft MVP [Windows Server] Datacenter Management

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.

    Wednesday, May 20, 2020 4:40 PM
  • Thanks Dave,

    In the second link - it's for 2016 which I dislike greatly about Microsoft (different documentation for different versions of the OS that may or may not apply to multiple) does state this:

    For optimal performance, we recommend that you attach multiple disks to a single virtual SCSI controller and create additional controllers only as they are required to scale the number of disks connected to the virtual machine.

    If that's the case, then we'll stick with one; I do wish they would keep up on each release on what is considered best practice / optimal performance tuning rather than rely on dated articles.

    It's the same with Storage Spaces: Their documentation on best configuration is from 2012r2 for most of it, despite massive changes in how SS (not S2D) handles things with ReFS in 2019 (And SAC of course) - the only way you find out about some of the tweaks/tuning is by working with Microsoft support or troubleshooting on your own.  To say nothing of literal PS Command options that exist for subsystems that have no definition or explanation on what they do. 

    Follow up question: does Microsoft HAVE more advanced reading on certain systems that just isn't available outside of buying a book or such?

    Thursday, May 21, 2020 1:31 AM
  • They're not the greatest at keeping the documentation current, somewhat understandable give the amount of it. I think any that mention Server 2016 should also apply to Server 2019 for most things. More to be found here on docs.microsoft.com

    https://docs.microsoft.com/en-us/windows-server/storage/storage

     

     




    Regards, Dave Patrick ....
    Microsoft Certified Professional
    Microsoft MVP [Windows Server] Datacenter Management

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.

    Thursday, May 21, 2020 2:14 AM
  • I have to admit I find that odd all the same.

    Fundamentally, there has to be some form of IO limit on the vSCSI controller.  I can't find anything that shows what the max queue depth or similar is, which is a main reason why you see the recommendations for segmenting high IO drives between multiple virtual controllers.  

    In that way, you can have the parallel operations at a better rate, just as 2-vCPU is better than 1; but just as with vCPU, it makes sense that you wouldn't want 4-vSCSI as you'll in theory start to hit limitations of the underlying storage itself.

    This is the deep understanding of virtualization that I try to keep myself up to date on, which is hard when there's so little documentation to this degree. 

    Thursday, May 21, 2020 4:06 PM
  • If further assistance is needed you can start a case here with product support.

    https://support.microsoft.com/en-us/hub/4343728/support-for-business

     

     



    Regards, Dave Patrick ....
    Microsoft Certified Professional
    Microsoft MVP [Windows Server] Datacenter Management

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.

    Thursday, May 21, 2020 4:14 PM
  • Hi tayschrenn,

    I'd like to check if you need any additional assistance on the forum? If yes, please feel free to feedback. If you would like to end this thread, please mark useful reply as answer.

    Thanks for your time!

    Best Regards,

    Anne


    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Wednesday, May 27, 2020 2:35 AM
    Moderator