[Xen-users] Fast write performance, slow read performance in NFS

[Linspeed <lee@xxxxxxxxxxxx>]

Hello

I need to setup shared storage for several virtual machines I'm running in
Xen.
I've gone for NFS.

Native performance on the disk that is shared is as follows:
Read: 199 MB/second
Write: 158 MB/second

Now I've done lots of testing with NFS options on the client (the virtual
machine).
I've managed to get the same write performance as I get natively, but read
performance is way below half that of native. Around 70 MB/second.

Current setup on the server:
/disks/shared   *(rw,async,no_root_squash,no_subtree_check)

/etc/fstab on the virtual machine:
host:/disks/shared /nfs nfs rsize=262144,wsize=262144,hard,intr,rw 0 0

I have tried lots of settings for rsize, but it makes no difference. wsize
did - I got large performance increases by increasing the wsize.

When I run mount -v:
nfs
(rw,rsize=262144,wsize=262144,hard,intr,addr=200.200.200.184,nfsvers=3,proto=tcp,mountproto=udp)

I am using openSUSE 11.0. Kernel is 2.6.27. This problem also exists with
kernel 2.6.25.

Has anyone else had this problem, and if so how did you solve it?

Thanks
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