[mythtv-users] [OT]Slow JFS writes over NFS

John Finlay finlay at moeraki.com
Fri Jan 29 02:46:46 UTC 2010

Cool Frood wrote:
> On Thu, Jan 28, 2010 at 3:23 PM, John Finlay <finlay at moeraki.com> wrote:
>> For historical reasons I have 3 mythtv disks that use JFS and 1 that use
>> XFS. I recently discovered that writes to the JFS filesystems over NFS are
>> much slower (1/5th) than the writes to the XFS filesystem over NFS. FTP
>> transfers are much faster as well to any disk.
>> I tried changing some of the NFS params but that didn't do anything. I even
>> cleared one of the JFS disks and reformatted it to XFS and NFS writes sped
>> up. AFAICT the only difference is the JFS filesystem.
>> I googled but couldn't find anyone experiencing similar problems with NFS
>> writes to a JFS filesystem.  Can anyone suggest a fix for this problem?
>> Thanks
>> John
> One of the things that I can think of is poor fsync() performance for
> JFS.  This is not a solution, but to test this theory, you could try
> exporting with an async flag on the NFS server and see what kind of
> performance you get with JFS vs. XFS.  If the async performance for
> JFS and XFS is comparable, then you don't have too much of a choice.
I didn't detail the things I tried but I did try setting the client and 
the server async flags and also tried udp instead of tcp but the result 
was the same.


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