[Gluster-users] Low (<0.2ms) latency reads, is it possible at all?

Marcus Bointon marcus at synchromedia.co.uk
Wed Apr 24 12:18:12 UTC 2013

On 24 Apr 2013, at 14:00, "Willem" <gwillem at gmail.com> wrote:

>> I'm testing GlusterFS viability for use with a typical PHP webapp (ie. lots
>> of small files). I don't care so much for the C in the CAP theorem, as I
>> have very few writes. I could live with a write propagation delay of 5
>> minutes (or dirty caches for up to 5 minutes).

We know that gluster's small-file performance isn't good, and since you can live with such long write propagation, reciprocal rsync could be a better and simpler solution. That way you'd get much faster local performance. The only issue really is that deletes aren't possible to propagate correctly with 2-way rsync (because a delete at one end is indistinguishable from an add at the other), but you may be able to live with it. csync2 aims to solve the delete issue with a transaction database, but I could never make it work.

To get a consistent 0.2ms off anything you're going to need to be on SSDs - you can't fit everything in your cache.

Marcus Bointon
Synchromedia Limited: Creators of http://www.smartmessages.net/
UK info at hand CRM solutions
marcus at synchromedia.co.uk | http://www.synchromedia.co.uk/

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