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Poor iSCSI Performance RRS feed

  • Question

  • Have an iSCSI target drive on Windows Server 2016 and an initiator on Windows Server 2012R2 Hyper-V host over a 10gbps copper Ethernet connection. The Hyper-V Windows Server 2012R2 VM is running an Oracle database and the performance is terrible. The VM has 2 separate SCSI controllers...the OS going to a VHDX on a host local drive and a second controller with a VHDX on the iSCSI drive containing Oracle.  Copying from the physical VM Host to the iSCSI drive seems okay, but any I/O to the iSCSI drive containing the VM Oracle drive just crawls.  Any ideas as to what the problem might be?
    Friday, October 18, 2019 9:05 PM

All replies

  • Hi,

    Thank you for posting in forum!

    There are several reasons why your problem may be caused:

    1. The performance of the Disk itself

    2. IO is large, but network bandwidth is not enough

    In order to verify the performance of the Disk, please help us to do the following tests, thank you in advance for your efforts.

    Test 1:

    I recommend you to disconnect the iscsi target server  and test the performance of the disk on the iscsi target server.

    Test 2:

    I recommend you to create a new VHDX on the iscsi target server, put only a little amount of files inside, and then see if its IO is still very bad. If the performance of I/O to the new iSCSI drive is ok , it may be because the database I/O is too large, but our network bandwidth is not enough which results in poor performance. If the performance of I/O to the new vhdx is also very poor, then the performance of the disk itself may be very poor, it is recommended that you contact the storage vendor or use a new disk.

    Hope this can help you.

    Best Regards,

    Lily Yang



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    Monday, October 21, 2019 8:51 AM
  • Thanks, Lily. The perfoprmance of the physical disk is fine. We shut down the VM and there are no problems with performance of the iSCSI disk when accessed from the Hyper-V host. We shut down the DB on the VM and the performance was still terrible, so it doesn't appear to be a DB I/O bottleneck problem either.
    Monday, October 21, 2019 4:45 PM
  • Hi,

    Please try  to completely disable the firewall and see if the ISCSI performance is still bad.

    Try to recreate a new VM with this VHD to see if it can work fine.

    Hope this can help you.

    Yours sincerely,

    Lily


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    Wednesday, October 23, 2019 9:12 AM
  • Hi,

    Just checking in to see if the information provided was helpful. 

    Please let us know if you would like further assistance.

    Best Regards,

    Lily

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    Friday, October 25, 2019 8:55 AM
  • Turning firewall off had no impact.  Have tried recreating new VM from scratch and no impact.
    Friday, October 25, 2019 8:20 PM
  • Hi

    Im sorry I don’t have any further suggestions for you. Or you can open a support case with Microsoft to help you work through it.

    Best regards,

    Lily



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    Monday, October 28, 2019 9:12 AM