On Fri, Mar 12, 2010 at 1:30 PM, Ric Wheeler <ricwheeler@xxxxxxxxx> wrote: > 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 > > I'm not sure. My servers are EC2 instances in Amazon's cloud computing service.I am doing the test from an EBS which is a virtual disk mounted locally on an instance and exported via NFS. So I don't think I can do any relevant tests locally. Thanks, Brandon -- 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
