[CentOS] unfsd scalability issues

Sat Jun 2 14:09:36 UTC 2012
Boris Epstein <borepstein at gmail.com>

On Sat, Jun 2, 2012 at 8:50 AM, Dennis Jacobfeuerborn <dennisml at conversis.de
> wrote:

> On 06/02/2012 02:16 PM, Boris Epstein wrote:
> > On Sat, Jun 2, 2012 at 6:16 AM, Johnny Hughes <johnny at centos.org> wrote:
> >
> >> On 06/01/2012 10:26 PM, Boris Epstein wrote:
> >>> On Fri, Jun 1, 2012 at 6:36 PM, John R Pierce <pierce at hogranch.com>
> >> wrote:
> >>>
> >>>> On 06/01/12 2:27 PM, Boris Epstein wrote:
> >>>>> I believe that unfsd (http://unfs3.sourceforge.net/  ) now does have
> >>>>> multi-threaded capability and as such should be fairly well
> scalable. I
> >>>> am
> >>>>> using it on CentOS 6.2 and it seems to become all but unusable when
> >> more
> >>>>> then 3-4 users connect to it. Is that normal? What sort of experience
> >>>> have
> >>>>> other people had?
> >>>> yeesh, wtf ?
> >>>>
> >>>>     latest version: 0.9.22    2009-01-05
> >>>>
> >>>> WHY?!??!   what problem is this supposed to solve over the built in
> >>>> native Linux NFS, which supports a lot more than just NFSv3?
> >>>>
> >>>>
> >>>> maybe in 2003, when Linux NFS was sketchy, this made sense.
> >>>>
> >>>>
> >>>> --
> >>>> john r pierce                            N 37, W 122
> >>>> santa cruz ca                         mid-left coast
> >>>>
> >>>>
> >>>>
> >>>> John,
> >>> The native NFS only supports the local file system (on the local disk).
> >>> What we have here is an NFS gateway to a distributed file system, in
> our
> >>> case MooseFS ( http://www.moosefs.org/ ).
> >>>
> >>
> >> You might take a look at GlusterFS for your distributed file system if
> >> most of your nodes are on the same 100mbit or 1Gbit network.  GlusterFS
> >> is the new "big thing" that Red Hat is going to support and we use it on
> >> the CentOS infrastructure and like it quite well.  It is also very easy
> >> to maintain and you can mount it via the glusterfs client or via NFS.
> >> It does not work real well across a slower internet like in multiple
> >> datacenters, but if your machines are all on a fast network with each
> >> other, I highly recommend it.
> >>
> >>
> >> John,
> >
> > I agree with you that GlusterFS is not bad - though neither is MooseFs,
> > based on all accounts, and MooseFS is very simple and lightweight, which
> > was why we chose it. At any rate, at this point this is what we are
> using.
> > All we need is an NFS gateway that would scale to 10-20 sessions without
> > losing too much performance.
> >
> > And yes, it could be that it is my MooseFS that is underperforming - I am
> > studying that possibility too.
>
> MooseFS is really only designed to host large files and to be useful if you
> care about throughput but not latency. GlusterFS is going to perform much
> better as a regular filesystem due to its consistent hashing approach and
> is just as simple and lightweigt as MooseFS.
>
> But why can't you mount MooseFS locally and then export it using the
> regular nfs implementation?
>
> Regards,
>  Dennis
>
> PS: You might also take a look at Ceph at ceph.com and Sheepdog at
> www.osrg.net/sheepdog. Both two very interesting contenders. You can find
> some interesting benchmarks for a 1000 node Sheepdog cluster here:
> http://sheepdog.taobao.org/people/zituan/sheepdog1k.html
>
> Regards,
>  Dennis
> _______________________________________________
>


Dennis,

Thanks for a thoughtful reply.

I believe the regular NFS does not allow you to export non-local
directories. That was so a few years ago; I didn't even check for myself
this time around as people are saying this is still the case. Perhaps I
should check.

When you are saying that MooseFS is high latency - what sort of latency
should I expect when accessing a file, though? There's a whole community of
happy MooseFS users out there; I am not sure they'd be so happy if you had
to wait for 30 seconds to just start reading a file. We could tolerate some
latency here, by the way.

Boris.