Hi Vikas, Mohit, I should disclose our typical use cases: We need to read and write files of size several 100s of MBs - the ratio of read : write is about 1:1. > What did you use to calculate latency? I used http://www.bitmover.com/lmbench they have a tool "lat_tcp". Numbers below are from lmbench tool "bw_tcp": > Network bandwidths: > dfs01: 54 MB/s > dfs02: 62.5 MB/s > dfs03: 64 MB/s > dfs04: 91.5 MB/s The setup is Gluster native, no NFS. About the "Optimizing Gluster" link - I have seen it before, but there are several things I don't understand: 1.) Tuning FUSE to use larger blocksize - when testing PVFS, we achieved best performance with bs = 4MB. It's hard to understand why it's hardcoded to 128 KB. Also I have read somewhere else (referencing FUSE) - that larger blocksize doesn't yield more performance. I guess when transfering larger amount of data on network with significant latency, a lot less IO requests should result in higher throughput. (And it's cheaper also on EBS). Are those listed adjustments to FUSE kernel modules still applicable? 2.) Enabling direct-io mode Does this work on current 3.1.2? : glusterfs --direct-io-mode=write-only -f <spec-file> <mount-point> also with --direct-io-mode=read-write ? Of those parameters in "Setting Volume Options", could this one help: - performance.write-behind-window-size - increasing 10-20 times? Now, the raw block device throughput (dd if=/dev/zero of=/path/to/ebs/mount bs=128k count=4096 oflag=direct) 3 measurements on server machines dfs0[1-4]: dfs01: 9.0 MB/s, 16.4 MB/s, 18.4 MB/s dfs02: 26.0 MB/s, 28.5 MB/s, 13.0 MB/s dfs03: 14.4 MB/s, 11.8 MB/s, 32.6 MB/s dfs04: 35.5 MB/s, 33.1 MB/s, 31.9 MB/s This, indeed, varies considerably! Thanks for help. Karol On Wed, Mar 23, 2011 at 7:06 PM, Vikas Gorur <vikas at gluster.com> wrote: > Karol, > > A few general pointers about EBS performance: > > We've seen throughput to an EBS volume vary considerably. Since EBS is iSCSI underneath, throughput to a volume can fluctuate, and it is also possible that your instance is on degraded hardware that gets very low throughput to the volume. > > So I would advise you to first gather some data about all your EBS volumes. You can measure throughput to them by doing something like: > > dd if=/dev/zero of=/path/to/ebs/mount bs=128k count=4096 oflag=direct > > The "oflag=direct" will give us the raw block device throughput, without the kernel cache in the way. > > The performance you see on the Gluster mountpoint will be a function of the EBS performance. You might also want to spin up a couple more instances and see their EBS throughput to get an idea of the range of EBS performance. > > Doing a RAID0 of 4 or 8 EBS volumes using mdadm will also help you increase performance. > > ------------------------------ > Vikas Gorur > Engineer - Gluster, Inc. > ------------------------------ > > > > > > > > >
