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Re: [Xen-users] DomU very slow over NFS




Considering that you are using PVM, try a benchmark with bonnie++ to check non sequential read and write on your NFS partition.

----
Alison Barros da Silva

On May 23, 2012, at 5:49 AM, Jude Pereira wrote:

Hi,
I'm having trouble setting up xen. Our VMs are on an NFS mount point.

/var/lib/nfs/xen_storage is mounted over NFS
If I cd to that directory, and I do a simple dd benchmark, it writes at 112 MB/s, The VM files are located here, they are preallocated from /dev/zero.
If I start one DomU, the write speed inside that VM is ~7 MB/s(measured via dd).

What could be the cause of this? If the VM is on local storage, then the write speeds are perfect(80 MB/s), but when they are over an NFS, they write very very slow.

It certainly is not a NFS issue, as I can write to it at 112 MB/s, in a mounted directory.

Any help is appreciated,


Thanks in Advance,
Jude

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