[Wlug] NFS Trouble

Chuck Haines chaines at gmail.com
Thu Sep 9 17:08:38 EDT 2004


I will try all of these things and get back to everyone on what I find
out.  Thanks a bunch for your help.

Chuck

On Thu, 9 Sep 2004 14:39:21 -0400, John Stoffel <stoffel at lucent.com> wrote:
> 
> Chuck> The  curent line from the fstab is as follows:
> Chuck> hostname:/home              /home                   nfs
> Chuck> rsize=4096,wsize=4096,bg,intr,rw,actimeo=15 0 0
> 
> Here's one of the problems, you're not specifying TCP here, and you're
> using pretty low numbers.  Try changing to use 32768 and tcp for your
> numbers.
> 
> Also, have you checked the duplex on server to make sure it's ok?  You
> mention you're using RAID on the server, I assume RAID5?  If so, what
> kind of stripe size are you using?
> 
> What does 'vmstat 1' (on the server) say from about 15 seconds before
> the copy kicks in, to about 15 seconds after the copy is done?
> 
> Does the time scale up linearly when you copy a 100mb file?  Or drop
> by half when you copy a 25mb file?
> 
> What filesystem are you using on the NFS server and do you have quotas
> or anything else like that setup?  How full is the filesystem?
> 
> What happens if you write a pair of 50 mb files at the same time from
> two different clients?  Does the time double?  Does the load double?
> 
> Basically, I don't know what's going on here, but I suspect:
> 
> 1. network speed/duplex mismatch - that you're seeing lots of timeouts
>    and retries on writes, but not reads.
> 
> 2. NFS needs tuning on the clients to write in bigger chunks
> 
> 3. You're RAID stinks.  Which reminds me, how much time does a write
>    from a non-raid disk on the server to the home directory/raid disk
>    take?  Can you time the write time of a 50mb file and if it's still
>    ugly, then you've narrowed down the issue.
> 
> Basically, there's alot of potential problems here and we need more
> details.
> 
> John
>    John Stoffel - Senior Unix Systems Administrator - Lucent Technologies
>          stoffel at lucent.com - http://www.lucent.com - 978-952-7548
> 



-- 
Chuck Haines
chaines at gmail.com
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