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Guest on Server 2012 Hyper-V very slow

    Question

  • Hi all,

    I am testing with Server 2012 Hyper-V but find the guess is very slow. The bottleneck should be disk IO, Resource Monitor showed 100% disk activity but only 500KB/s throughput. I did notice the post Slow SMB3 and iSCSI as Hyper-V VM storage because of unbuffered I/O and StarWind (free edition) did improve the performance but still slow.

    My machine is home-made:

    ASUS P8P67 (Motherboard)

    Intel i7-2600K 3.40GHz * 4 Core (8 logical Processor)

    8G RAM

    Windows Server 2012 Standard (6.2.9200 build 9200).

    Drive D: Western Digital 3TB SATA 3 disk (on SATA 3 port)

    I created new Windows XP (32-bit) Guest on a dedciated drive (D:) without starwind

    When guest running, do something cause the disk 100% active time but only about 500KB/s throughout. At the moment, the system disk (C:) is ~0% disk activity.

    Simple file copy to D: on host Server results in 100% active time but over 50MB/s (Write) throughput.

    I would like to know if Hyper-V still hardcoded to use unbuffered IO in release version? If so, any way to increase the performance without using StarWind like software?

    Thanks.

    KC


    • Edited by kcip Sunday, October 07, 2012 2:41 AM
    Sunday, October 07, 2012 2:16 AM

Answers

  • Hi,

    Thanks for your advises.

    In order to indentify if it is the Server 2012 problem, I put back the old Win2008R2 HD (host OS) and try. The same problem occurred also although its performance was acceptable in the old days. So I turned my focus on the newly added 4 HDs which forms a software RAID.

    I unplug those HDs and the response did improve. So I searched the update BIOS (2012 Sep) and patched the motherbroad. After several test, the VM performance becomes acceptable with those RAID disk attached.

    So I would conclude this is be BIOS bug that performance degrade with increase in attached HD.

    No matter how, I still want to know if "unbuffered IO" setting remain in release version.

    Anyway, thanks all of you.

    KC

    • Marked as answer by kcip Wednesday, October 10, 2012 2:14 PM
    Wednesday, October 10, 2012 2:13 PM

All replies

  • Hello,

    Did you check other vm's such Windows 7 or Windows Server 2008 on this Hyper-V.

    Did you install the integration components on XP machine?

    Eli.


    אירוע Unified Communication User Group יצא לדרך, המפגש יתקיים בתאריך ה-28.6 בשעה 17:30. אשמח לראותכם.

    Sunday, October 07, 2012 12:51 PM
  • Hi all,

    I am testing with Server 2012 Hyper-V but find the guess is very slow. The bottleneck should be disk IO, Resource Monitor showed 100% disk activity but only 500KB/s throughput. I did notice the post Slow SMB3 and iSCSI as Hyper-V VM storage because of unbuffered I/O and StarWind (free edition) did improve the performance but still slow.

    My machine is home-made:

    ASUS P8P67 (Motherboard)

    Intel i7-2600K 3.40GHz * 4 Core (8 logical Processor)

    8G RAM

    Windows Server 2012 Standard (6.2.9200 build 9200).

    Drive D: Western Digital 3TB SATA 3 disk (on SATA 3 port)

    I created new Windows XP (32-bit) Guest on a dedciated drive (D:) without starwind

    When guest running, do something cause the disk 100% active time but only about 500KB/s throughout. At the moment, the system disk (C:) is ~0% disk activity.

    Simple file copy to D: on host Server results in 100% active time but over 50MB/s (Write) throughput.

    I would like to know if Hyper-V still hardcoded to use unbuffered IO in release version? If so, any way to increase the performance without using StarWind like software?

    Thanks.

    KC


    Yes, there are other solutions doing caching and I/O acceleration (for example from VeloBit, Virsto and FlashSoft) utilizing either RAM or flash or both. And either using or not using log-structuring to eliminate random I/O. But they are not free as StarWind.

    Yes, Windows can use buffered I/O if you'd configure so-called CSV cache but... It's 1) limited size 2) slow and inefficient write-throu (should be write-back) and 3) caches reads only (writes are problems as multi-VM I/O pattern is entirely random, think about "I/O scrambler").

    Yes, you can use software to fix slow hardware but in your case it's something wrong with a config (software or hardware) as numbers you publish are unacceptable. Use something fast and stable to check I/O performance in a parent partiton and inside of a VM. I'd recommend ATTO Disk Benchmark for the beginning (followed by Intel I/O Meter, NAS Toolkit and SQLIO and JetStress).

    -nismo

    • Proposed as answer by VR38DETTMVP Sunday, October 07, 2012 6:35 PM
    • Marked as answer by kcip Wednesday, October 10, 2012 2:14 PM
    • Unmarked as answer by kcip Wednesday, October 10, 2012 2:14 PM
    Sunday, October 07, 2012 6:35 PM
  • Hi,

    Thanks for your advises.

    In order to indentify if it is the Server 2012 problem, I put back the old Win2008R2 HD (host OS) and try. The same problem occurred also although its performance was acceptable in the old days. So I turned my focus on the newly added 4 HDs which forms a software RAID.

    I unplug those HDs and the response did improve. So I searched the update BIOS (2012 Sep) and patched the motherbroad. After several test, the VM performance becomes acceptable with those RAID disk attached.

    So I would conclude this is be BIOS bug that performance degrade with increase in attached HD.

    No matter how, I still want to know if "unbuffered IO" setting remain in release version.

    Anyway, thanks all of you.

    KC

    • Marked as answer by kcip Wednesday, October 10, 2012 2:14 PM
    Wednesday, October 10, 2012 2:13 PM
  • Hi,

    Thanks for your advises.

    In order to indentify if it is the Server 2012 problem, I put back the old Win2008R2 HD (host OS) and try. The same problem occurred also although its performance was acceptable in the old days. So I turned my focus on the newly added 4 HDs which forms a software RAID.

    I unplug those HDs and the response did improve. So I searched the update BIOS (2012 Sep) and patched the motherbroad. After several test, the VM performance becomes acceptable with those RAID disk attached.

    So I would conclude this is be BIOS bug that performance degrade with increase in attached HD.

    No matter how, I still want to know if "unbuffered IO" setting remain in release version.

    Anyway, thanks all of you.

    KC

    Yes, all VHD(X) I/O is unbuffered (unless you've configured a CSV cache and in that case you have write-thru block level cache accelerating reads only).

    -nismo

    Thursday, October 11, 2012 9:25 AM