In regard to: [Networker] Data Domain in mixed BOOST/VTL mode?, bingo said...:

Why do you really want to use VTL at all?

I didn't say I wanted to -- in fact, it would be my preference that we
didn't.  However, our SAN folks are advocating the VTL attachment for
the clients that have SAN storage.

Using a DD you are talking to very fast network-attached AFTDs where NW
8 clients can even use new technologies like Flexible Blocksize & Direct
File Access. The data rates which you achieve here are amazing,
especially when you stream data from various clients to multiple AFTDs
and - at the same time - simulteanously clone data from these devices to
tape (if needed at all).

We understand all that, but I think you're focused on the backup
aspect.  If we have to do a full restore of a 1.8 TB volume, all the
data still has to be transferred from the DD to the client.  Client direct
and de-dupe isn't going to help us there.

So, in theory (hah!) it should be much faster to restore a large volume
over our 4 GiB SAN than it would be to pull it all back over a 1 GiB
TCP/IP link.

My opinion is to avoid VTLs whenever possible. Yes, you have fast SAN
access but IMHO this is the the only benefit. You really force a disk to
behave like a tape and in general, you add an additional, unnecessary
'layer' which limits the flexibility B2D would offer. And of course it
is a an additional component which potentially might cause trouble. Just
avoid it!

I'm not disagreeing with you Carsten, but unless there are some
significant gotchas with using a DD in mixed mode, I don't think any of
that reasoning is going to hold out against the potential for greater
restore speeds.

Tim
--
Tim Mooney                                             Tim.Mooney AT ndsu DOT 
edu
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