[Gluster-users] small write speed problem on EBS, distributed replica

[Vikas Gorur]

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.

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Vikas Gorur
Engineer - Gluster, Inc.
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