Re: Slow NFS

[Andrew Reid <reidac@bellatlantic.net>]

On Saturday 02 January 2010 10:55:18 Chris Davies wrote:
> I'm curious whether anyone has good a decent read/write speed using NFS
> (v3 or 4) between a number of Debian "testing" based systems.
>
> I've got one box exporting a number of filesystems using NFS v3, and
> three others mounting various combinations of those file systems. I
> see less than 10% disk throughput on the remote boxes that on the local
> one. Switched gigabit LAN throughout.
>
> I'd expect some hit, but 90% degredation seems awfully high.

  There is a performance-tuning section in the NFS Howto,
with several tips, including simple tests for measuring performance.
<http://nfs.sourceforge.net/nfs-howto/ar01s05.html>

  My own experience with NFS on a server with several tens of
clients is that the biggest determiner of performance is the type
of file operations you're doing.  Anything that requires many 
seek operations, like grepping for complicated regular expressions,
or writing data character-by-character, will do very poorly.  
Things that operate sequentially, or in very large chunks, do 
much better.  In general, copying is fast, searching is slow.

  I think NFSv4 is much the same, although it may introduce 
a few more options, and so be more tunable.  I have no direct
experience with it.

				-- A.
-- 
Andrew Reid / reidac@bellatlantic.net