10:09 a.m.
another point is, that a correct configured multipathing is way more solid
when it comes to a single path outage. at the software side, i have seen
countless nfs servers which where unresponsive because of lockd issues for
example, and only a reboot fixed this since its kernel based.
another contra for me is, that its rather complicated and a 50/50 chance
that a nfs failover in a nfs ha setup works without any clients dying.
dont get me wrong, nfs is great for small setups. its easy to setup, easy
to scale, i use it very widespread for content sharing and homedirs. but i
am healed regarding vm images on nfs.
On Thu, Jan 9, 2014 at 8:48 AM, Karli Sjöberg <Karli.Sjoberg(a)slu.se> wrote:
On Thu, 2014-01-09 at 08:35 +0100, squadra wrote:
> Right, try multipathing with nfs :)
Yes, that´s what I meant, maybe could have been more clear about that,
sorry. Multipathing (and the load-balancing it brings) is what really
separates iSCSI from NFS.
What I´d be interested in knowing is at what breaking-point, not having
multipathing becomes an issue. I mean, we might not have such a big
VM-park, about 300-400 VMs. But so far running without multipathing
using good ole' NFS and no performance issues this far. Would be good to
know beforehand if we´re headed for a wall of some sorts, and about
"when" we´ll hit it...
/K
>
> On Jan 9, 2014 8:30 AM, "Karli Sjöberg" <Karli.Sjoberg(a)slu.se>
wrote:
> On Thu, 2014-01-09 at 07:10 +0000, Markus Stockhausen wrote:
> > > Von: users-bounces(a)ovirt.org [users-bounces(a)ovirt.org]" im
> Auftrag von "squadra [squadra(a)gmail.com]
> > > Gesendet: Mittwoch, 8. Januar 2014 17:15
> > > An: users(a)ovirt.org
> > > Betreff: Re: [Users] Experience with low cost NFS-Storage
> as VM-Storage?
> > >
> > > better go for iscsi or something else... i whould avoid
> nfs for vm hosting
> > > Freebsd10 delivers kernel iscsitarget now, which works
> great so far. or go with omnios to get comstar iscsi, which is
> a rocksolid solution
> > >
> > > Cheers,
> > >
> > > Juergen
> >
> > That is usually a matter of taste and the available
> environment.
> > The minimal differences in performance usually only show up
> > if you drive the storage to its limits. I guess you could
> help Sven
> > better if you had some hard facts why to favour ISCSI.
> >
> > Best regards.
> >
> > Markus
>
> Only technical difference I can think of is the iSCSI-level
> load-balancing. With NFS you set up the network with LACP and
> let that
> load-balance for you (and you should probably do that with
> iSCSI as well
> but you don´t strictly have to). I think it has to do with a
> chance of
> trying to go beyond the capacity of 1 network interface at the
> same
> time, from one Host (higher bandwidth) that makes people try
> iSCSI
> instead of plain NFS. I have tried that but was never able to
> achieve
> that effect, so in our situation, there´s no difference. In
> comparing
> them both in benchmarks, there was no performance difference
> at all, at
> least for our storage systems that are based on FreeBSD.
>
> /K
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