Richard Rhodes said:

>I'd love to have a couple vtl's.  When we've priced them out they come
>out to be much more costly (several times) that of tape for our
>environment.  We keep lots of old/stale data around which drives seems
>to drive the cost of the VTL way up.  I was hoping possibly use a vtl
>for only primary data with the new feature of TSM v5.4, but that's not
>going to work out.

VTL cost (even after dedupe) will never compare with the cost of tape
media alone, so tape will always be a cheaper medium if you take it out
of the library.  When I say that VTLs are close to the price of tape, I
mean close to the price of a similarly-sized, fully-populated-with-media
tape library.

>I personal opinion is that VTL's are a stop-gap solution.  I think
>compression and de-dupe have much wider application within a normal
>disk subsystem where it could apply to a much wider range of
>situations.  

Pretty much everybody who is following the industry believes it will
morph into the "intelligent disk target" industry.  VTL will continue to
be a personality they offer, but as other backup software products are
better able to back up to filesystems (TSM does it just fine), more VTL
vendors will offer a filesystem interface.  Right now, the only one that
does a filesystem interface and de-dupe is Data Domain.  (Copan has a
filesystem interface, but I don't think they're doing de-dupe through it
yet.  Any day now.)

>This is the bit problem I see with Tape.  It seems to me that the
>latest generations of tape drives have rated speeds that almost
>defy the any ability to supply them with data.  I almost which
>I could purchase a modern tape drive that actually was slower.

Mmm...   LTO-4: 120 MB/s native speed, 180 MB/s typical with
compression.  (I'm using 1.5:1 compression, which is what I see most
often as an average actual compression ratio.)  So...  It wants 180
MB/s, and I've supposed to feed that with a 60-80 MB/s GbE connection.
(The only saving grace of modern tape drives is that they have variable
speeds.  The LTO-4, for example, can go as slow as about 40 MB/s plus
compression.)

The problem is capacity.  As vendors push capacity, they do so by
pushing the bits closer together.  As they do that, the drive gets
faster.