[lug] Stale NFS data

[Alan Robertson]

John Hernandez wrote:
> We have 4 RH8.0 NFS clients with ro mounts to a RH8.0 server
> 2.4.20-28.8smp.  The files on the server are changed once every 3 hours
> by a remote rsync.  Following the rsync job, some clients still see the
> old version of the file, even though it appears the timestamp has
> changed.  The only way to get the clients back up to date is to remount
> the filesystem.
> 
> Has anyone seen this before?  We tried the 'noac' option to mount_nfs,
> but the resulting loads are too high and performance is dismal.

If the clients have the files open, then you're probably just screwed. 
By design, NFS has no consistency/integrity :-(

If they are opening them later, then maybe playing with acdirmax (and 
friends) might help...

If you have some freedom to modify the application, one way of forcing 
the directory content to be re-cached on demand is to (try to) create a 
file in the directory (crude, but helpful in some circumstances).

Maybe something like this after the rsyncs occur would be helpful??

Of course, if things are mounted ro, that's probably not too helpful :-(

Or maybe use mount -o remount would be less disruptive than unmounting 
and remounting?  (or maybe that's what you did).


-- 
     Alan Robertson <alanr at unix.sh>

"Openness is the foundation and preservative of friendship...  Let me 
claim from you at all times your undisguised opinions." - William 
Wilberforce