Re: [Xen-users] Xen SAN Questions

["Ricardo J. Barberis" <ricardo.barberis@xxxxxxxxxxxx>]

El Martes 27 Enero 2009, Tait Clarridge escribió:

> >> Second, I ran a test on two identical servers with DRBD and GFS in a
> >> Primary/Primary cluster setup and the performance numbers were appalling
> >> compared to local ext3 storage, for example:
> >
> >Yes, cluster filesystem have lower performance than non-cluster
> > filesystems, due to the former performing lokcs on files/dirs.
> >Add DRBD replication on top of that and performance will be lower.
>
> So maybe I should use DRBD in a non-clustered setup?

Someone else should answer this, as I stil had no experience with DRBD, but 
maybe using it in active-passive mode could improve things, at the expense of 
having unusable storage (?)

> I used both noatime and nodiratime but I recently destroyed the GFS setup
> in preparation for testing DRBD+XFS+NFS exporting

Alright, I have a GFS partition with no quota for sharing VM config files 
between the xen hosts. I'll try to make some benchmarks with and without 
quota to see the impact on performance.

> >> - Experiment with DRBD again with another Filesystem (XFS?) and have it
> >> re-exported as NFS to both machines (so they can both bring up VMs from
> >> the "pool")
> >
> >I guess NFS could work, unless you have too many machines using it
> > (Linux's NFS sucks)
>
> There would only be two machines using it with a 3rd if there was some
> planned maintenance.

OK, then you shouldn't have major issues.

> >Check the thread with subject "disk backend performance" from November 27,
> >2008. There started a very nice discussion involving Thomas Halinka and
> >Stefan de Konink about AoE vs. iSCSI (thank you both!).
> >
> >Also, the thread with subject "lenny amd64 and xen" will be of your
> > interest, on November 27 Thomas started a description of his self-build
> > SAN which is very insightful.
>
> Alright, I will check those out after I finish some more testing.
>
> Thanks a lot for the reply, if I find anything I will report it back here.
>
> All the best,
> Tait Clarridge

Ceers,
-- 
Ricardo J. Barberis 
Senior SysAdmin - I+D 
Dattatec.com :: Soluciones de Web Hosting 
Su Hosting hecho Simple..! 

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