Hyper-V Cluster CSV low performance RRS feed

  • Question

  • Hello, 

    I have hyper-v cluster with two nodes connected to iSCSI array(12 SSDs RAID 10) via 4x SFP+ NICs each node.
    There is 2x Netgear M4300 12x12f switchs  between nodes and array.
    Before create CSV read/write speeds at attached LUN was arround 3000/2000MBs, after create CSV 700/400MBs

    is it normal ? I want to move 30x hyper-v VMs to new environment, but im affraid of low performence.


    Friday, July 17, 2020 7:40 AM

All replies

  • Hi Wutuch,

    1. We may run Cluster validation of the Cluster storage to check if there's anything wrong with the storage.

    2. If there's no error or warning of the cluster, then from the Cluster, we have limited things to check the performance issue.

    3. As far as I'm concerned, the current speed will be fine for the live migration, however, live migration also related with network bandwidth.

    Thanks for your time!

    Best Regards,


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    Monday, July 20, 2020 8:57 AM
  • Hi,

    thanks for your answer. There is no error from cluster validation.

    Nodes have dedicated SFP+ ports for live migration, and it works fine.

    The question is that the csv performance downgrade, compared to speed before CSV configuration is normaly ?

    • Edited by Wutuch Monday, July 20, 2020 9:45 AM
    Monday, July 20, 2020 9:37 AM
  • How did you perform your test?  What was the disk ownership?  If you were performing the test to a CSV that was performing redirected writes, it would be expected that the performance would be significantly lower.


    Monday, July 20, 2020 12:27 PM
  • Test was performed by CrystalDiskMark at CSV folder. There is no VMs running at now. There is no difference in test result between owner and non-owner node. I know that can be little slower, but 12x read intensive SSDs in RAID10 should be much faster then 700mb/s.

    Monday, July 20, 2020 1:33 PM
  • Hi Wutuch,

    Thanks for your feedback. After some research, I'm afraid to say I didn't find more information to provide due to some limitation. If you would like to troubleshoot the CSV IOPS performance deeply, I would suggest you open a case with MS:


    Best Regards,


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    Monday, July 27, 2020 7:16 AM