[Linux-cluster] GFS2 with IMAP Maildir server

[Ian Hayes]

On Fri, Jul 3, 2009 at 2:00 PM, Gordan Bobic <gordan at bobich.net> wrote:

> Flavio Junior wrote:
>
>> On Fri, Jul 3, 2009 at 4:40 PM, Gordan Bobic <gordan at bobich.net <mailto:
>> gordan at bobich.net>> wrote:
>>
>>
>
>  Well, no problem at al to migrate to GFS1, actually I've already thinked
>> about it, but all those gfs1 tunning options and tests makes me a bit
>> apprehensive.
>>
>
> GFS1 doesn't have any more tuning options than GFS2 that I can think of.
> And besides, in practice, if the performance isn't in the right ball park
> out of the box, no amount of tweaking will help. Just about the only think
> that makes a significant difference is the noatime mount option. I wouldn't
> bother with the rest unless you really need those last few percent.


Noatime helps, but where I've seen some really good performance boosts is in
tweaking glock_purge and demote_secs parameters. Of course, always start
with a modest setting and start tweaking from there. Playing around with
statfs_fast =1, noatime, nodiratime and playing withe glock settings, I've
seen a pretty significant jump in performance.


>
>  I'll wait a bit more for GFS2 community, if they say that it can't be done
>> I go to GFS1 or even ocfs2 (what is the third option, as I've already a RHCS
>> structure with clvmd).
>>
>
> The problem with GFS2 is that it's still a bit buggy, as you've found. But
> there isn't that much difference in performance between various similar file
> systems. Sure, GFS2 is faster than GFS1, but it's not an order of magnitude
> faster.


I've done some GFS vs GFS2 performance benchmarking for a cluster that I
will be putting in soon. I've found that GFS1 performance has been much much
better than GFS2. As far as I can tell, GFS2 lacks a lot of the tunability
that GFS1 has. All the documentation I've seen says that it's supposed to be
self-tuning, so there are fewer performance tuning options you have to play
with. From my tests, I've had almost a 50% reduction in performance using
GFS2.
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