[Gluster-users] GlusterFS performance

[Brian Candler]

On Fri, Mar 01, 2013 at 03:30:07PM +0600, Nikita A Kardashin wrote:
>    If I try to execute above command inside virtual machine (KVM), first
>    time all going right - about 900MB/s (cache effect, I think), but if I
>    run this test again on existing file - task (dd) hungs up and can be
>    stopped only by Ctrl+C.
>    Overall virtual system latency is poor too. For example, apt-get
>    upgrade upgrading system very, very slow, freezing on "Unpacking
>    replacement" and other io-related steps.
>    Does glusterfs have any tuning options, that can help me?

If you are finding that processes hang or freeze indefinitely, this is not
a question of "tuning", this is simply "broken".

Anyway, you're asking the wrong person - I'm currently in the process of
stripping out glusterfs, although I remain interested in the project.

I did find that KVM performed very poorly, but KVM was not my main
application and that's not why I'm abandoning it.  I'm stripping out
glusterfs primarily because it's not supportable in my environment, because
there is no documentation on how to analyse and recover from failure
scenarios which can and do happen. This point in more detail:
http://www.gluster.org/pipermail/gluster-users/2013-January/035118.html

The other downside of gluster was its lack of flexibility, in particular the
fact that there is no usage scaling factor on bricks, so that even with a
simple distributed setup all your bricks have to be the same size.  Also,
the object store feature which I wanted to use, has clearly had hardly any
testing (even the RPM packages don't install properly).

I *really* wanted to deploy gluster, because in principle I like the idea of
a virtual distribution/replication system which sits on top of existing
local filesystems.  But for storage, I need something where operational
supportability is at the top of the pile.

Regards,

Brian.