On 03/12/2010 01:22 PM, Brandon Simmons wrote:
I am using tiobench to test performance of an NFS mounted volume, and
notice that Sequential Reads are much slower than Random Reads. This
isn't the behavior when I run the same test on the disk mounted
locally.
For random reads I'm getting:
50 MB/s over NFS
v.s
384 MB/s when mounted locally
This is in comparison to the benchmark for _Random Reads_, in which I get:
288 MB/s both over NFS _and_ when directly mounted
The other benchmarks seem to be in line with what I would expect, but
I'm fairly new to NFS. Why would sequential reads over NFS be sooo
much slower than random reads over NFS?
I am exporting the volume on the server like this
/export *.internal(no_subtree_check,rw,no_root_squash)
and mounting with this:
mount -o hard,intr,async,noatime,nodiratime,noacl $NFS_SERVER:/export /nfs
Additionally I am doing all this in amazon EC2, exporting an EBS
volume with the XFS file system (redundant, I know).
I have tried using jumbo frames and various other mount options, but
none seem to have much effect.
Thanks for any clues.
Not sure what kind of network you are running the NFS test over so it is
quite hard to figure out why your performance varies so wildly.
Normal NFS testing with a gigabit network between the client and server
would be much closer to 50MB/sec than your 288MB/sec.
Can you try to reproduce this locally with known client and server hardware?
ric
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
