Re: [Xen-users] iscsi vs nfs for xen VMs

[Pierre <pierre@xxxxxxxxxx>]

Rudi Ahlers <Rudi@xxxxxxxxxxx> a écrit :

> On Thu, Jan 27, 2011 at 1:04 PM, Adi Kriegisch <adi@xxxxxxxxxxxxxxx> wrote:
>
> > > What do you then do if you want redundancy, between 2 client PC's, i.e
> > > similar to RAID1 ?
> > Oh well, there are several ways to achieve this, I guess:
> > * use dm mirroring on top of clvm (I tested this once personally but did
> >  not need it for production then -- will probably look into it some time
> >  again).
> >  I think this is just the way to go although it might be a little slower
> >  than running a raid in domU.
> > * Giving two LVs to the virtual machines and let them do the mirroring with
> >  software raid.
> >  I think this option offers greatest performance while being robust. The
> >  only disadvantage I see is that in case of failure you have to recreate
> >  all the software raids in your domUs. In some hosting environments this
> >  might be an issue.
> Why not just give the 2 LV's to the dom0, and raid it on the dom0
> instead? The the domU's still use the "local storage" as before and
> they won't know about it.
With that setup, are you able to do live migration ?

> > * Use glusterfs/drbd/... Performancewise and in terms of reliability and
> >  stability I do not see any issues here. But to use those you actually do
> >  not need a SAN as a backend. A SAN always adds a performance penalty due
> >  to an increase of latency. Local storage always has an advantage over SAN
> >  in this respect. So in case you plan to use glusterfs, drbd or something
> >  like that, you should reconsider the SAN issue. This might save alot of
> >  money as well... ;-)
> I would prefer not to use DRBD. Every layer you add, adds more
> complication at the end of the day.
>
> And we already have this expensive EMC SAN, so I would like to utilize
> it somehow, but with better redundancy.
--
Pierre

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