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

To: Matej Zary <matej.zary@xxxxxxxxx>
Subject: Re: [Xen-users] iscsi vs nfs for xen VMs
From: Rudi Ahlers <Rudi@xxxxxxxxxxx>
Date: Wed, 26 Jan 2011 10:55:41 +0200
Cc: "jg@xxxxxxxxxxxx" <jg@xxxxxxxxxxxx>, Dustin Black <vantage@xxxxxxxxxxxx>, "xen-users@xxxxxxxxxxxxxxxxxxx" <xen-users@xxxxxxxxxxxxxxxxxxx>
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On Wed, Jan 26, 2011 at 10:44 AM, Matej Zary <matej.zary@xxxxxxxxx> wrote:
> Depends on quality of NAS/SAN device. Some of them are more reliable&robust 
> that rest of the infrastructure (dual controllers, raid6, multipathing etc.), 
> obviously they cost arm&leg. So they SHOULD not totally fail (firmware issues 
> are  another thing though). And in that case, even if one owns enterprise 
> grade storage, backups (tape, another storage, remote site) are always must. 
> Yeah, if storage fails, there will be downtime. You can still have locals 
> disks on xen host. So for example you can restore most important Xen guests 
> on the local disks from backups and live without live migration until the 
> NAS/SAN issues are solved.
> Matej
> ________________________________________

Well, that's the problem. We have (had, soon to be returned) a so
called "enterprise SAN" with dual everything, but it failed miserably
during December and we ended up migrating everyone to a few older NAS
devices just to get the client's websites up again (VPS hosting). So,
just cause a SAN has dual PSU's, dual controllers, dual NIC's, dual
HEAD's, etc doesn't mean it's non-redundant.

I'm thinking of setting up 2 independent SAN's, of for that matter
even NAS clusters, and then doing something like RAID1 (mirror) on the
client nodes with the iSCSI mounts. But, I don't know if it's feasible
or worth the effort. Has anyone done something like this ?

Kind Regards
Rudi Ahlers

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