[CentOS] nfs high load issues

Monty Shinn montys at videopost.com
Fri Jul 18 13:43:25 UTC 2008


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 

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.



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