Re: kvm-83 write performance raw

[Anthony Liguori <anthony@codemonkey.ws>]

Malinka Rellikwodahs wrote:
> Host: 2.6.27-gentoo-r8 AMD Opteron 2378
> Guest: Windows XP SP2
>
> when running with a raw disk image as a file or a raw disk image on an
> lvm vg, I'm getting very low performance on write (5-10 MB/s) however
> when using qcow2 format disk image the write speed is much better
> (~30MB/s), which is consistant with a very similar setup running
> kvm-68.  Unfortunately when running the test with qcow2 the system
> becomes unresponsive for a brief time during the test.
>
> kvm -localtime -m 1024 -drive file=<diskimage>,boot=on
>
> where diskimage is either the qcow2 format image, or the path to the lv
>   
What version of kvm is this?  Is it kvm-68?  You'll have better luck 
with something newer than that.

Regards,

Anthony Liguori

> The host is running raid5 and drbd (drive replication software),
> however performance on the host is performaning well and avoiding the
> drbd layer in the guest does not improve performance, but running on
> qcow2 does.
>
> Any thoughts/suggestions of what could be wrong or what to do to fix this?
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