NetApp’s TR3428, Storage best Practices for VMware, states to set the fractional reserve to 0%, so there is no overhead for a LUN.

Cheers,
 
Vaughn Stewart | Virtualization Evangelist











From: "Buerger, Andreas" <andreas.buerger@wincor-nixdorf.com>
Date: Wed, 5 Mar 2008 10:05:45 +0100
To: Milazzo Giacomo <G.Milazzo@sinergy.it>, <toasters@mathworks.com>
Subject: RE: R: VMware - snap - backup

Yes, I agree to your statement regarding iSCSI SAN.
We've made the same experience, but not with the ESX iscsi solution.

>The biggest problem on iSCSI (or
>F/C) is the oversizing (double) you've to let on volume for snapshot of
>VMFS stores, the restore that from a snapped LUN is not so easy (I
spoke
>of Vizioncore or Tomato to add value to VM backup, but is another cost)
>and so on.

If I got it right, you've set fractional_reserve of the volume to 100%.
You can decrease this amount, so that you can save a lot of space.
In relation to this you can setup vol autosize and snap autodelete, to
secure your LUNs.
These are pretty functions given by OnTAP.


-----Original Message-----
From: Milazzo Giacomo [mailto:G.Milazzo@sinergy.it]
Sent: Tuesday, March 04, 2008 9:02 PM
To: Buerger, Andreas; Nick Silkey; toasters@mathworks.com
Subject: R: R: VMware - snap - backup

Only to answer to your question.

>I would be interested in the reason, why you have chosen iscsi instead
of nfs. Just because of the license costs?


The cost of license could be a reason, over all if you consider the
tiering appliend on 3000 or 6000 family but the real reason is that
we've a loto f environment where db with great I/O demand (Exchange with
hundreds of mailboxes, Oracle, SQL with dozens of GB of db and so on...)
installed on iSCSI SAN using only software initiator (such as the
Microsoft) and with great user perception and benchmarked performance.

We also are aware that NFS on NetApp filer is really fast (think to
Oracle, also RAC, on NFS!) but up to know we've used for VMware only in
limited and little farm of ESX servers. The biggest problem on iSCSI (or
F/C) is the oversizing (double) you've to let on volume for snapshot of
VMFS stores, the restore that from a snapped LUN is not so easy (I spoke
of Vizioncore or Tomato to add value to VM backup, but is another cost)
and so on.

Anyway, for any 'transport' you choose to use you can be sure that on
NetApp appliances VMware will perform always better than other storage.

PS) just as sample we've setup a VMware cluster on a filer without F/C
switches, using a direct attach and letting igroup and lun masking act
as switch :-)...this you can have with FAS only!


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