You can't share a single LUN/filesystem with two servers unless you
share it via NAS or some really cutting edge global filesystem software.
Once you do that, the cost justification of "just using disk" goes out
the window.

And, yes, I think that storage node A being able to copy storage node
B's backups is essential in a lot of designs.  For example, consider a
storage node that's just backing up itself.  It's only got enough time
to do the backup, and does not have the time to do the copy.  Then you
have a "real" storage node do the copy.  It's also important for highly
available restores.  All "regular" storage nodes should be able to
access each other's backups.  One goes down and another can do its
restores or backup -- IF it can access the other servers' backups.  With
a VTL or dedupe NAS that's a piece of cake.  It's NOT easy with plain ol
disk.

---
W. Curtis Preston
Backup Blog @ www.backupcentral.com
VP Data Protection, GlassHouse Technologies 
-----Original Message-----
From: EMC NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On
Behalf Of Dag Nygren
Sent: Tuesday, November 06, 2007 11:43 PM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: Re: [Networker] VTL or disk cabinet backup

> I would suggest that what you describe is not shared.  First, you
would
> have to size each LUN appropriately for each server.  Some LUNs will
> always be too big, and some LUNs will always be too small.

Not if you use the same filesystem, just different directories.

>  In addition,
> you can't have storage node A back up to disk slice A, then have
storage
> node B clone storage node A's backups, cause it can't see them.  If
you
> could, that would be sharing.

Do you really need that?

Best
Dag

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