[Gluster-users] GlusterFS performance
Nikita A Kardashin
differentlocal at gmail.com
Tue Mar 12 08:56:28 UTC 2013
I found other strange thing.
On the dd-test (dd if=/dev/zero of=2testbin bs=1M count=1024 oflag=direct)
my volume shows only 18-19MB/s.
Full network speed is 90-110MB/s, storage speed - ~200MB/s.
Volume type - replicated-distributed, 2 replicas, 4 nodes. Volumes mounted
via fuse with direct-io=enable option.
Its sooo slooow, right?
2013/3/5 harry mangalam <harry.mangalam at uci.edu>
> This kind of info is surprisingly hard to obtain. The gluster docs do
> some of it, ie:
> I also found well-described kernel tuning parameters in the FHGFS wiki (as
> another distibuted fs, they share some characteristics)
> and more XFS tuning filesystem params here:
> and here:
> But of course, YMMV and a number of these parameters conflict and/or have
> serious tradeoffs, as you discovered.
> LSI recently loaned me a Nytro SAS controller (on-card SSD-cached) which
> pretty phenomenal on a single brick (and is predicted to perform well
> based on
> their profiling), but am waiting for another node to arrive before I can
> it under true gluster conditions. Anyone else tried this hardware?
> On Tuesday, March 05, 2013 12:34:41 PM Nikita A Kardashin wrote:
> > Hello all!
> > This problem is solved by me today.
> > Root of all in the incompatibility of gluster cache and kvm cache.
> > Bug reproduces if KVM virtual machine created with cache=writethrough
> > (default for OpenStack) option and hosted on GlusterFS volume. If any
> > (cache=writeback or cache=none with direct-io) cacher used, performance
> > writing to existing file inside VM is equal to bare storage (from host
> > machine) write performance.
> > I think, it must be documented in Gluster and maybe filled a bug.
> > Other question. Where I can read something about gluster tuning (optimal
> > cache size, write-behind, flush-behind use cases and other)? I found only
> > options list, without any how-to or tested cases.
> > 2013/3/5 Toby Corkindale <toby.corkindale at strategicdata.com.au>
> > > On 01/03/13 21:12, Brian Candler wrote:
> > >> 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
> > >> 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<
> > >> anuary/035118.html>
> > >>
> > >> The other downside of gluster was its lack of flexibility, in
> > >> 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.
> > >> 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
> > >> of
> > >> a virtual distribution/replication system which sits on top of
> > >> local filesystems. But for storage, I need something where
> > >> supportability is at the top of the pile.
> > >
> > > I have to agree; GlusterFS has been in use here in production for a
> > > and while it mostly works, it's been fragile and documentation has been
> > > disappointing. Despite 3.3 being in beta for a year, it still seems to
> > > have
> > > been poorly tested. For eg, I can't believe almost no-one else noticed
> > > that
> > > the log files were busted.. nor that the bug report has been around for
> > > quarter of a year without being responded to or fixed.
> > >
> > > I have to ask -- what are you moving to now, Brian?
> > >
> > > -Toby
> > >
> > >
> > > ______________________________**_________________
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> > > Gluster-users at gluster.org
> > > http://supercolony.gluster.**org/mailman/listinfo/gluster-**users<
> > > upercolony.gluster.org/mailman/listinfo/gluster-users>
> Harry Mangalam - Research Computing, OIT, Rm 225 MSTB, UC Irvine
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> "Something must be done. [X] is something. Therefore, we must do it."
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With best regards,
differentlocal (www.differentlocal.ru | differentlocal at gmail.com),
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