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Terrible disk performance inside VM RRS feed

  • Question

  • I am running Windows Server 2012 R2 with a VM running in Hyper-V. Prior to this host being 2012 R2, it was 2008 R2 but this problem existed then, too. I wiped 08 R2 and installed 2012 R2.

    We have awful performance from within the virtual machine in Hyper-V.

    Below are two screenshots that demonstrates what performance monitor displays from within the VM.

    It will write, it will stop, it will resume.

    Its VHD files are stored on a ReadyNAS 4220X connected by iSCSI. We are unable to upgrade to VHDX because it is one half of a DAG and you cannot have mixed VHD/VHDX. There is another VM still powered off that has the same problem and it has been converted to VHDX.

    I have tried a number of different configurations:

    Multiple NICs connected with MCS to bonded NICs (LACP) on the ReadyNAS. (192.168.13.x)
    Standalone NIC connected to bonded NICs on the ReadyNAS. (192.168.13.X)
    Standalone NIC connected to the same bonded ReadyNAS NICs. (10.1.1.X)
    Standalone NIC connected to the standalone NIC on the ReadyNAS. (10.1.1.X)

    The 192.168.13.X network is dedicated to iSCSI traffic and the 10.1.1.X is our production LAN through a different physical switch, just to illustrate that I have attempted different ways of pinning down the problem.

    If I copy directly to the iSCSI target from the host machine, transfer is normal. If I copy from another machine on the network from within the problem VM, the transfer itself is fast but when it goes to write to the drive, we will see the terrible performance issue. 

    The RAID volume on the ReadyNAS is completely dedicated to this VM at this point. There is nothing else running on it. I have disabled the checksumming on the volume that can sometimes cause issues and have disabled TCP offloading as suggested in all documents detailing fixes for poor iSCSI performance. The machine is fully patched and, as I said at the beginning, this issue existed in both Server 2008 R2 and Server 2012 R2. The host machine is a Dell PowerEdge R610.

    Wednesday, February 5, 2014 6:21 PM

All replies

  • I assume that your tests are all network copy based.

    If your NICs support "Virtual Machine Queues" / "VMQ" disable it and try again.


    Brian Ehlert
    http://ITProctology.blogspot.com
    Learn. Apply. Repeat.
    Disclaimer: Attempting change is of your own free will.

    Wednesday, February 5, 2014 7:12 PM
    Moderator
  • My tests are all network copy based but even if I copy a file within the VHD, this happens. Bootup is extremely slow as well. I disabled Virtual Machine Queues on the host, no change.
    Wednesday, February 5, 2014 7:26 PM
  • Hi clg666,

    Sorry for the misunderstanding .

    "My tests are all network copy based but even if I copy a file within the VHD, this happens"

    Does it mean you mount the VHD file on target server , when you copy file from another machine to the VHD the performance  is still bad ?

    According to this "If I copy directly to the iSCSI target from the host machine, transfer is normal" , It is likely VHD file problem .

    Please try to copy the VHD to another place and mount it then run "chkdsk" to check it .

     

    If it is the case ,

    Best Regards

    Elton Ji


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    Sunday, February 9, 2014 1:44 PM
    Moderator
  • From Netgear's support get new firmware ! Very well!

    Notable changes since ReadyNASOS 6.1.8

    1. [RC1] Update kernel with various filesystem and iSCSI improvements.
    2. [RC2] Make Richcomm-based UPS devices work.
    3. [RC2] Add DLNA support for FLV.
    4. [RC2] Avoid issue with too many open file descriptors in some odd AD environments.
    5. [RC3] Various security updates. (OpenSSL, GNUTLS)
    6. [RC4] Fix periodic log truncation.
    7. [RC5] Add UI option to configure sync policy for iSCSI LUNs.

    ReadyNASOS 6.1.9 [RC5]


    Have a nice day !!!

    Monday, July 14, 2014 10:28 AM