Re: client apps not surviving nfsd restart

[Bernd Schubert <bernd-schubert@web.de>]

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Hello Frank,


> 1) After installing SusE 9.0, the default was set to nfs-over-tcp. I didn't
>     know that, but suddenly after every server reboot I had at least 4-5
>     of the work station users complaining about stale NFS handles, e.g.,
>     /usr was stale and so java didn't start anymore etc. It's not really
>     reproducable by some certain sequence of starting apps and rebooting
>     the server etc., but it happens every time the server has to reboot
>     with a few clients.

can you confirm this with vanilla client/server kernel version? We have 45 
diskless clients here and each of them has no problem on a server reboot. 
This works for more than two years with vanilla 2.4.X kernel versions. Since 
about 4-5 month we also use nfs-over-tcp and this also has no negative 
effect.
We also tried using 2.6.7 on our server, but it always crashed every morning 
with page allocation errors, so we had to give up with this version and 
switched back to 2.4.X. However, although the server was rebooted every 
morning (and/or the failover server took over), this caused no problems for 
the clients (except for the directories mounted from ClusterNFS, but thats a 
different more complicated CNFSD related story).

>
>     In the NFS howto I read that the disadvantage of nfs-over-tcp is that
>     "If your server crashes in the middle of a packet transmission, the
>      client will hang and any shares will need to be unmounted and
> remounted."

This howto seems to be slightly outdated.

>
>     But I thought a clean reboot with a clean stop and later start of the
>     nfsserver shouldn't make a problem.

It doesn't make a problems with vanilla kernel version.

[snip]

>
> 2) We are currently testing kernel 2.6.8.1. The nfs behaviour seems
>     to have changed in some ways. Running e.g. "find /" on a diskless
>     client with kernel 2.4 would just hang when the server rebootet
>     and later go on when the server was back.
>     With 2.6.8.1, the find command will immediately abort and report
>     some stale nfs handles.

We only tested 2.6.7 and it caused no such problems, as we have failover, I 
tested failover during file transfers and this worked like a charm.


Cheers,
	Bernd

PS: About 1.5 years ago we were forced to use a Suse kernel on our server (due 
to a closed-sources binary only kernel module) and this kernel caused a lot 
of nfs related trouble for us. As the module also didn't work properly we 
finally decided not to buy this software ;)


-- 
Bernd Schubert
Physikalisch Chemisches Institut / Theoretische Chemie
Universität Heidelberg
INF 229
69120 Heidelberg
e-mail: bernd.schubert@pci.uni-heidelberg.de

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