[mythtv-users] NFS + 3ware = slow

[Trey Boudreau]

On Sat, Mar 11, 2006 at 10:44:03AM -0700, James C. Dastrup wrote:
> 
> I just got a 3ware 7506-4 based on recommendation from this group.
> I'm having problems with writing to the RAID-5 array over NFS.
> Here's some averaged samples using the cp command:
> 
> Samba (reading): 20 MB/s
> Samba (writing): 20 MB/s
> NFS (reading): 40 MB/s
> NFS (writing): 4 MB/s   <---- ??????
> 
> Also interesting, the first 500 MB of data when writing over NFS
> goes at about 50 MB/s, and then it slows to a crawl. RAID-5 array
> is formatted JFS. CPU stays low on both machines. I've tried endless
> amounts of mount options: sync,async, rsize=[1042-32768], 
> wsize=[1024-32768], lock, nolock, hard, soft, intr, tcp, udp, 
> nfsvers=33, etc. iperf is showing a raw transfer rate of 66 MB/s.
> 
> Has anyone seen anything similar? Does anyone know any debugging
> tools or commands so I can see exactly where the slowdown is
> occurring?
>
I remember reading (but can't remember where) that 2.6.15 has issues
with NFS.  You didn't mention your kernel version, but if you run
2.6.15 you might hunt for patches or downgrade to 2.6.14.  What Googling
I did seems to point to problems on the client side.

-- Trey