[CentOS] slow NFS speed

nate centos at linuxpowered.net
Wed Jul 30 12:40:18 UTC 2008

Mag Gam wrote:
> I am using mode 0, which is an aggregate.
> I have 2 clients, which are bonded too.
> MB, sorry :-)

That's totally different then, 80MBytes/second is very fast.
What kind of storage is behind the NFS?

Run iostat -x 1 100 on the server while your doing the test.
Look at the last column, what's the reading?

In my experience the typical I/O size for requests is in the
20kB range, in which case a 10k RPM disk will run at about
2.2-2.5MBytes/second(before latency spikes). Depends what your
transferring though. Cache of course can mask this to some

If your using gigE across the board you may be able to
get more performance by using 9k jumbo frames. Though I
would only use jumbo frames on secondary interfaces
dedicated for storage as jumbo and non jumbo traffic doesn't
mix well. Of course any network devices in between the systems
must support/be configured for jumbo frames as well. In Linux
at least as far as I can frame size is determined by the
interface itself, so e.g. you can't run two VLANs on one NIC,
one in jumbo and one not in jumbo. It's either on or it's off.
(Unlike switches where you can do both on the same port)

If your going to be routinely pushing a gigabit worth of NFS
traffic I certainly would ditch Linux and get a more robust
NAS box.


More information about the CentOS mailing list