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Monty Shinn 07-18-2008 01:43 PM

nfs high load issues
 
Greetings.

When I "pull" data from server A to server B, with nfs, server B reports
a high load when viewed via uptime. The load is upwards of 6.x. Server
A's load remains light. When I "push" the data, server A's and B's
loads are relatively light.


When I change the mount point from nfs to cifs, I don't see this
problem. I also don't have this problem using scp.


I don't recall seeing these excessive load factors when these servers
ran Centos 4.x. I have noticed these problems with 5.1 and 5.2. I
updated the servers from 5.1 to 5.2 yesterday.


I actually have 3 servers set up the same way, and all 3 exhibit the
same problem.


iostat reports nothing unusual - the cpu idle percentage hovers around
the high 80's to 90's.


I am not seeing any network errors or collisions when viewed via
ifconfig. These servers are on a gigabit network, connected via a good
3Com switch. I am getting transfer rates averaging around 55MB/sec
using scp, so I don't think I have a network/wiring issue. The nics are
intel 82541GI nics on a Supermicro serverboard X6DH8G. I am not
currently bonding, although I want to if the bandwidth will actually
increase.


Both server's filesystems are ext3, 9TB, running raid 50 on a 3Ware
9550SX raid card. I have performed the tuning procedures listed on
3Ware's website. The "third" server has an XFS filesystem, and the same
problem exists.


I am using the e1000 driver (default on install). The servers are 64
bit, and have 2 gigs of memory. Adding memory didn't help the situation.


I have tried turning autoneg off on the nic. They are running
1000baseT, full duplex. I have varied the nfs rsize and wsize
parameters to no avail.


I am using nfs v3. nfsv4's configs seem quite a bit different, and I
haven't had a chance to familiarize myself with the changes.


Any ideas or suggestions would be greatly appreciated.

TIA,

Monty
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