CentOS - May 2008 - I need some NFS explanations, please.

I have a problem with NFS that I can't start to resolve. All servers are 
CentOS 5 servers. One server exports a directory and two others mount 
it. Simple so far.

A file is created on the server, and the two nfs clients do an "ls
-al"
and get a common (meaning the same) result as the server. Over the 
course of a day, and after the file on the server has been modified on 
the server, the results of the "ls -al" show the original common
result
on the two clients, and an obviously different result on the server. So 
I figure it's some kind of caching problem. But I figure it's a server 
caching problem.

I next go to one of the clients and "cat" the file, and then do
another
"ls -al". Now the server and this client agree on the file attributes,
but not on the second client which shows the original wrong result 
still. So now I think it's a client caching problem.

Can anyone explain the above situation and perhaps some settings that 
will resolve this without requiring the nfs client to open the file in 
some way before it gets the proper file attributes?

"nfsstat -m" of the client returns the following:

 Flags: 
rw,vers=3,rsize=32768,wsize=32768,acregmax=3,acdirmin=3,acdirmax=3,hard,
intr,proto=tcp,timeo=600,retrans=2,sec=sys,addr=10.0.12.152


Thanks for any help.

Steve Campbell

On Tue, May 20, 2008 at 8:22 AM, Steve Campbell <campbell at cnpapers.com>
wrote:
> I next go to one of the clients and "cat" the file, and then do
another "ls
> -al". Now the server and this client agree on the file attributes, but
not
> on the second client which shows the original wrong result still. So now I
> think it's a client caching problem.
>
> Can anyone explain the above situation and perhaps some settings that will
> resolve this without requiring the nfs client to open the file in some way
> before it gets the proper file attributes?
Try explicitly adding "noac" (no attribute caching) to the mount
definition in /etc/fstab.  If you're doing this as an autofs mount, it
goes in /etc/auto.* somewhere, with a slightly different syntax.