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Hyperv Windows 2003 Guest Low disk write speed RRS feed

  • Question

  • Hi Guys,

    Setup:

    W2K8 Sp2 HyperV host with W2K3 sp2 guest running exchange 2003 sp2.

    Issue:

    Users are complaining about slow outlook response.  Checking Process I/O it is indicated the issue is with exchange information Store. CPU usage load is very low.

    Performance monitor is showing high average disk Queue on the exchange store disk.

    If I run Bench32 on the guess system I get a maximum write speed of 50MB/sec, yet on the host I get a maximum write speed of 400MB / Sec.

    I believe that the issue with the server is the slow disk write performance. I would like to know why it is so slow and how to improve it.

    Has anyone got any ideas on this?

    Thanks for your help in advance.

    Regards

    Craig


    Craig

    Monday, September 17, 2012 7:05 AM

Answers

  • Hi Kakkarot,

    Just checking how many virtual process you have assigned to the 2003 virtual machines. 2003 actually runs slower when assign more processor than 2. I read somewhere that this is related to how 2003 interacts with processors.  This may effect your disk performance on the virtual guest. I know that it help resolve some of my performance issues.

    Craig


    Craig

    • Marked as answer by Craig Garland Friday, February 16, 2018 3:19 AM
    Thursday, October 3, 2013 11:04 PM

All replies

  • I have same problem.

    Hyper-V 2012 Server - host.

    Windows 2003 R2 - VM.

    Prior to installing actualizations on VM and Host i had like 100+ MB/s linear writting speed.

    After i have 14MB/s linear writting speed.

    Does anyone know what is a cause of this degradation, or perhaps KB number i should uninstall?

    I narrowed problem to Hyper-V host itself. On completly new VM with Windows 2003 R2 (without actualizations) there is exact same problem - 14MB/s writting.

    Strangly on host (Hyper-V Server) i can manage 100MB/s transfer between 2 separate disks - so problem exists in virtualization layer.

    kb2871777 - the only actualization I can not (Hyper-V do not allow deinstallation) and I did not uninstall.

    Problem still exists so as for now i point out this actualization to be a cause of all I/O problems.

    On 2012 Standard problem exists too... so its not related to Windows 2003 in any way.

    Be sure not to install actualizations to Hyper-V 2012... on machine You can't format on the spot.

    • Edited by Kakkarot Thursday, October 3, 2013 3:09 PM
    Thursday, October 3, 2013 10:06 AM
  • Hi Kakkarot,

    Just checking how many virtual process you have assigned to the 2003 virtual machines. 2003 actually runs slower when assign more processor than 2. I read somewhere that this is related to how 2003 interacts with processors.  This may effect your disk performance on the virtual guest. I know that it help resolve some of my performance issues.

    Craig


    Craig

    • Marked as answer by Craig Garland Friday, February 16, 2018 3:19 AM
    Thursday, October 3, 2013 11:04 PM
  • Well as problem exists on both 2003 and 2012 Server, it's clearly not an issue.

    However i tried that aproach and nothing changed in terms of writting speed for better. Whats more intresting... reading and writting speed dropped by more than 30% on 2 virtual processor machine in comparition to 8 virtual processor machine. (r/w: 100/100 hyper-v host,  100/14 windows server 2003/2012 on 8 processors, 70/8 windows server 2003 on 2 processors).

    So to sum it up - VM has 8-14% writting speed of HOST depending on number of processors assigned to VM (the more the better).

    After testing hardware with "pendrive xp" low performance might be related to disk controller or lack of proper drivers.

    I will reinstall hyper-v and make some aditional tests, but as for now I can not exclude for 100% hardware.

    I am not exactly sure if its driver or hardware related problem - after complete power-off of machine (completely unpluged from electricity), problem disapeared. My wild guess is that disk controler wasn's properly initialized during system boot, as previous settings were not cleared completely.

    Anyway it's good to know that problem is not Hyper-V 2012 related.

    • Edited by Kakkarot Tuesday, October 8, 2013 11:23 AM
    Friday, October 4, 2013 9:31 AM