Re: [Xen-users] Xen guest nfs client not responding

[tmac <tmacmd@xxxxxxxxx>]

it could be a few different things...

1. check the physical cables. use a good, comprehensive tester (not those cheap testers)
-> make sure there is no physical damage to the cable
-> make sure the ends are crimped properly (sheath is under the rj45 pincher)
2. Verify the capability of your NFS server. Many NFS server based on general purpose OS's
cannot do more than an 8K rsize/wsize. You must adjust your client to match.
-> if you have a netapp, the default could be 8K or 32K. run "options nfs" to find out
3. Verify the connectivity at the switches.
-> Make sure there are no duplex mismatches. (this should not happen at Gige, but happens all the time on 100BT)
-> If using GigE, verify Flow Control and, if possible, set it to on in both directions.
---> some switches do not support flow control in both directions

Hope this helps...

--tmac

On Jan 31, 2008 4:12 PM, Mark Furner <mark.furner@xxxxxxx> wrote:

Hello

I'm trying to get my NFS Xen vm guest systems to their host via NFS (within the same machine but keep getting performance-related errors):

nfs: server [IP] not responding, still trying
nfs: server [IP] OK
[loops]

Connectivity is flaky at best and applications running within the Xen guests keep crashing or freezing as a result.

There is a note at a LTSP site that says NFS has problems with the 2.6 Kernel and discrepancies in NIC capacity between the host and client if the NFS block sizes are too large:
http://wiki.ltsp.org/twiki/bin/view/Ltsp/NFS#NFS_Server_not_responding
Does this apply to Xen too?
Their fix: pass on kernel options to the NFS client. How could I try this with Xen?

Thanks for any help!

M
--
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-- 
--tmac

RedHat Certified Engineer #804006984323821 (RHEL4)
RedHat Certified Engineer #805007643429572 (RHEL5)

Principal Consultant, RABA Technologies

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