Hi Dave,

On 18/7/06 10:58 AM, "Werth, Dave" <dave.werth AT GARMIN DOT COM> wrote:

> This is a little off topic from the original question on this thread but
> regarding backup to disk, in anyone out there using a 'Virtual Tape
> Library'?  I don't recall seeing them addressed on the list.  It seems to me
> you could use one for relatively high speed backups then clone them to a
> real tape for offsite disaster recovery purposes.  I gather that they
> emulate existing tape libraries so would EMC have any special licensing in
> that regard or just treat them like an existing library?
> 
> We were considering adding 'Backup to Disk' this year but it appears to me
> that a VTL might be simpler and less costly in regards to licensing.  I'd
> like to learn more.
> 
> Any comments?

VTL's can have their place, but the key thing to remember is that they
emulate _all_ aspects of a tape library, both good and bad. That means:

- Not being able to simultaneously backup to and recover from the same media

- Having a limit on the number of active devices (yes in theory you wouldn't
want to create too many disk backup devices either, but it's a little
different here)

- Having a limit on the number of simultaneous recovers you can do - i.e.,
if you have the VTL configured to present 4 tape drives, then if you want to
recover from 5 different backups each on different virtual-tapes, one of
those recoveries will have to wait longer, etc.

Not saying these are insurmountable problems, but you do have to remember
that you emulate some of the bad aspects of libraries as well.

Cheers,

Preston.

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