Re: [Gluster-devel] general performance translator recommendations

[Vikas Gorur]

Here are the _general_ guidelines for using performance translators:

* write-behind: Almost always helps on the client side, because it
decreases write latency for applications. Using it is a good idea.

* io-threads: Almost always helps on the server side. We recommend
using it just below the protocol/server translator.

* read-ahead: Helps on the client side if your applications read files
in sequential order a lot.

* io-cache: Using io-cache on the client side would make sense if you
have a bunch of data that is frequently used (for example, a bunch of
small image files that are needed for every page on a website). Also,
as you said, if you have a lot of RAM, you might find io-cache useful.

As for io-threads above/below unify, there is not much to be gained by
using io-threads on the client side, since there are no slow
operations on the client side (just a straight code path from the
application to the server). Using it on the server makes sense because
it lets GlusterFS do other useful work while one thread is waiting for
a read/write from/to the underlying filesystem finishes.

You might also want to look at the booster shared library which can
provide a major performance enhancement.

Vikas
-- 
Engineer - Z Research
http://gluster.com/