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I have an NFS file server that exports mounts to 55 workstations. Occasionally the DHCP lease on the workstation IP addresses expire and get reissued new IP addresses. Unfortunately I think this causes the file server to hang (suddenly it takes 60 seconds to log in, another 60 seconds to load 'top', etc.) When I examine the CPU load or top I don't see any load on the server. Rebooting everything doesn't help.

When I encountered this problem before, my solution involved shutting off all the workstations, purging the NFS server (I'm running ubuntu server 10.04), rebooting the server, reinstalling NFS, then bringing the workstations back online.

I am not 100% sure this is the problem, but my only hint is that 'showmount' shows more IP addresses than there are workstations. I'd like know if there is some way to determine if there is a hanging NFS request, or to purge all existing requests, or hear suggestions on what else might be the problem.

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why are the workstations issued new ips n the first place? –  Joris Aug 23 '10 at 6:28
    
Because there's a layer of IT bureaucracy. :) Any ideas on how to handle the slowdown? –  Rich Aug 23 '10 at 13:08
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1 Answer

up vote 1 down vote accepted

I found that the sync mount option in NFS was just too slow for the amount of file accesses required by 20 people logging into gnome desktops. Changing the mount option to async speeded things up significantly.

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Presumably your NFS server doesn't have a RAID controller with battery backed write cache? Ours has (well, it's a SAN array), and we run ~100 desktops with sync mounted homes with no problems. –  janneb Oct 19 '10 at 13:59
    
a writeback cache is conceptually similar to the async option. having it on battery is equivalent to the server's UPS (it is on UPS, right?) –  Javier Oct 19 '10 at 14:41
    
@janneb Nope, we're pretty primitive with a software RAID 1. –  Rich Oct 19 '10 at 18:20
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