improving concurrency/performance

[Robert Mueller]

> >> In our experience FS-wise, ReiserFS is the worst performer between ext3,
> >> XFS e ReiserFS (with tailBLAH turned on or off) for a Cyrus Backend (>1M
> >> mailboxes in 3 partitions per backend, 0.5TB each partition).
> >
> > Interesting ... can you provide some numbers, even from memory?
> 
> 
> I'd also be VERY interested since our experience was quite the opposite. 
> ReiserFS was faster than all three, XFS trailing a dismal third (also had 
> corruption issues) and ext3 second or even more dismal third, depending
> on 
> if you ignored it's wretched large directory performance or not. 
> ReiserFS 
> performed solidly and predictably in all tests.  Not the same could be
> said 
> for XFS and ext3.  This was about 2 yrs ago though.

This was also our experience. ReiserFS was the fastest, most stable, and
the most "predictable" of the 3.

The concept of "predictable" is an interesting one. Basically we were
doing lots of tests including a bunch of simultanoues load tests (do
some cyrus tests, and at the same time do a bunch of other things that
caused lots of IO on the system) and what we found was that while ext3
in particular seemed to jump around performance wise a lot (it seemed to
strangely allocate a lot of IO for a while to cyrus, then slow down to a
crawl, then speed up again, etc) reiserfs performed very consistently
during the entire test. No idea what caused this, but was an interesting
observation.

My previous post on the filesystem topic as well...

http://permalink.gmane.org/gmane.mail.imap.cyrus/15683

Rob

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