On 8/19/11 8:04 PM, Patrick M. Landry wrote:
------------------------------------------------------------------------
*From: *"Alexander J. Maidak" <[email protected]>
*To: *"Patrick M. Landry" <[email protected]>
*Cc: *[email protected]
*Sent: *Wednesday, August 17, 2011 9:07:12 PM
*Subject: *Re: [lopsa-tech] Poor NFS performace from CentOS5
client to Oracle (Sun) Unified Storage NAS
Is the filer more then 80% full? Is it slow for writes and reads or
just writes? How slow is slow and what do you expect "fast" to be?
It is not more than 80% full. The speed problem is most noticeable when
asking for a listing in the directory with the 7000 subdirectories. It
is not
uncommon for that command to take 30 seconds to a minute or more to
complete from the CentOS5 hosts. It doesn't take more that 5 seconds
on the Solaris hosts.
Are you sure this is a NFS problem? Are you using LDAP for user
lookups? With that many directories, I can see there being slowness in
having to translate those UIDs/GIDs. This would definitely result in
some of the delays you are seeing.
Also, have you tried tuning the default mount options on the CentOS
client? The default rsize and wsize values are rather small for servers
on a gigabit LAN. Increasing them will give you substantially better
performance. Depending on your network, you may have slightly better
performance with UDP as well.
Are you seeing lots of metadata or data misses? If you go into
analytics and select ARC Accesses broken down by hit/miss then select
metadata misses broken down by l2arc eligibility this should give
you a
hint if your filer needs more l2arc to support the additional metadata
load of all those files.
I haven't been collecting those long-term but at the moment the
ratio of data hits to data misses is about 1 to 3. The ratio of
metadata hits to metadata misses is 80 to 1.
--
patrick
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