NFS problem

[Darin Perusich]

what OS are your nfs clients running? there are know problems between 
solaris and redhat 7.x and some 6.x. i did quite a bit of research into 
this back in january for a grid cluster i was putting together, check 
out this post. 
http://runlevelzero.net/pipermail/warewulf/2003-January/000100.html

are you getting any errors like "kernel: nfs: task 2752 can't get a 
request slot"? i saw errors like this when i ran into nfs problems, the 
nfs server was solaris with linux clients in this instance.


S. Johnson wrote:
> I have 2 client systems that need to access a mail volume via NFS.  I 
> believe it is an optimization/setup problem, but am unsure of what to 
> try to resolve it.  Here's the setup:
> 
> Server 3 - NFS Server, redhat 8.0, exporting /users from a fiber channel 
> array it hosts.  Mail is sent to and picked up to users home 
> directories, so there is a lot of disk access happening with read and 
> writes (4500 users).  /etc/exports looks like this:
> 
> /db     192.168.1.0/255.255.255.0(rw,no_root_squash)
> /isp    192.168.1.0/255.255.255.0(rw,no_root_squash)
> /users  192.168.1.0/255.255.255.0(rw,no_root_squash)
> 
> For now, the main export I am concerned with is /users, however, all 
> these partitions are on the same fiber channel raid and are still 
> accessed by the clients.  Traffic on the other two shares in pretty 
> minimal, but may still be a factor in overall performance of the system.
> 
> Servers 1 and 2 are configured to be able to run Postfix or 
> courier-imap, and access the /users share from server 3 via NFS.  Here 
> is the /etc/fstab the clients use:
> 
> server3:/db    /db    nfs bg,nfsvers=3,rsize=8192,wsize=8192 0 0
> server3:/isp   /isp   nfs bg,nfsvers=3,rsize=8192,wsize=8192 0 0
> server3:/users /users nfs bg,nfsvers=3,rsize=8192,wsize=8192 0 0
> 
> Servers 1 and 2 are able to mount and read the volumes fine when there 
> is little or no traffic.  However, when you move either Postfix or 
> Courier-imap services over to them, they eventually (after several 
> hours) start to have NFS problems.  After a while, there will be 
> hundreds of dead processes still hanging around and the load average 
> skyrockets (200 or more).  The mounts to /users or the other two are not 
> available.  Executing a df or mount command hangs your terminal.  
> Sometimes you can kill off processes and restart NFS services, other 
> times it requires a reboot of the client and usually means doing it by 
> powering off the machine because it hangs on the NFS processes and will 
> not shut them down.
> 
> Is there a tried and true way to setup NFS between the server and 
> clients that will support high volumes of traffic?  If anyone knows of a 
> better way to setup things the client and/or server side, please let me 
> know.
> 
> Thanks,
> 
> Sean Johnson
> 
> 
> 


-- 
Darin Perusich
Unix Systems Administrator
Cognigen Corp.
darinper at cognigencorp.com