NFS problem

[Robert Meyer]

Well, first thing that I would do is change the mount options to add the 'soft'
option:
server3:/users /users nfs bg,soft,nfsvers=3,rsize=8192,wsize=8192 0 0

If you don't want to do soft mount, then add the 'intr' parameter to make hard
mounted nfs I/O interruptable.  This means that a hung process can be
interrupted by a signal which causes the I/O call to return 'EINTR' to the
calling process.

I would start looking at your networking parameters in all three systems.  This
sounds like you might be on a 100baseT network and you're having connectivity
problems.  On your switches, lock the ports that the servers are on to
100BaseT-FD (100 Mbit, Full Duplex).  Then do the same on each machine with the
'mii-tool --force 100baseT-FD'.

Cheers!

Bob

--- "S. Johnson" <zatharus at ncn.net> 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
> 


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