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Re: [Xen-users] Poor Windows 2003 + GPLPV performance compared to VMWare

On 16/09/12 23:50, Dion Kant wrote:
> Adam,
> Can you give it a retry with the Windows DomU running from a file container?
> mount another LV somewhere on dom0 (e.g. /var/lib/xen/images/windows)
> Use "qemu-img convert your.vmdk -O raw
> /var/lib/xen/images/windows/disk0.raw" to create the file container
> I see significant disk I/O performance improvement on all my Windows
> DomU's when running them from file containers as compared to running
> them directly from a block device.
I'd really like to try this and see if it helps, but I'm not sure how I
can achieve that. The dom0 machine has a 60GB SSD drive internally, and
the VM is 230G, so I don't think I can put it on the local system.

Also, I don't think I would need to convert it, the disk is already in
raw format... I should be able to simply do:
dd if=/dev/sdX of=disk0.raw
where sdX is whatever disk linux has assigned to this iSCSI device.

In any case, I can't do this at this stage. About the only thing I could
consider would be to make a copy of the VM onto another host (not on the
SAN) and share that to the dom0 using NFS, which would then get me a
file based image (over NFS) to HDD backed storage. Though I think this
is changing far too many factors to really be useful (the SAN is SSD
backed btw).

Finally, I was always of the impression that physical devices provided
better performance due to lower overhead. I presume you are suggesting
better performance from RAM based caching on the dom0.

disk = [

Could I simply change that line to this:
disk = [

Since a device is just a file... or would that not make a difference?

OK, well, it doesn't work:
Error: Disk image does not exist: /dev/sdd
(well, originally it had the above path, but I tried the direct /dev/sdd
and same error).

Any further suggestions please?


Adam Goryachev
Website Managers

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