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Re: 2.4.18 XFS 1.1 : Gave up on XFS - too many Oops

To: Walter R Fletcher <fletcher@xxxxxxxx>
Subject: Re: 2.4.18 XFS 1.1 : Gave up on XFS - too many Oops
From: Andi Kleen <ak@xxxxxxx>
Date: Wed, 24 Jul 2002 19:27:06 +0200
Cc: linux-xfs@xxxxxxxxxxx
In-reply-to: <Pine.GSO.4.10.10207240849290.4211-100000@xxxxxxxxxxxxxxxxx>
References: <Pine.GSO.4.10.10207240849290.4211-100000@xxxxxxxxxxxxxxxxx>
Sender: owner-linux-xfs@xxxxxxxxxxx
User-agent: Mutt/
>      Initially I used the SGI XFS ISO (RH7.1 I think) to set
> the system up.  The system ran OK except for frequent rpc timeout
> problems reported by the NFS clients but only during write operations.
> The problem could be made to happen by setting processes running on
> each client which wrote data to the NFS server at the fastest rate
> possible, i.e.:
>     dd  if=/dev/zero  count=<bignumber>  bs=<various>  of=/big/file


A common problem with many older linux kernels is that NFS is using a 64K
socket buffer only. This can cause packets to get dropped when the buffer
queue is overloaded on the NFS server. What you can do is to increase
/proc/sys/net/core/[rw]mem_{default,max}. This has to be done before the
kernel nfs server is initialized, e.g. in the NFS server start script
before the daemons are started.
Newer kernels should do the tuning automatically. Same can be done on 
the clients.

Another common cause for dropped packets is a Ethernet half/full duplex
mismatch between switch and server. May be worth checking for.


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