Actually VTLs can still serve a good purpose with TSM.  The ability of
some to emulate a 3584 makes setup and management very easy, and some
use disk MUCH more efficiently than TSM would just doing file class
devices.  Also the mount, and seek times are virtually eliminated on
VTLs (if properly implemented).  The key with TSM is speed, and if they
"do" Deduplication then that's just a side benefit.  If I can buy a VTL
with 60 TB of Disk space that uses 90% of that space efficiently, and
then has hardware compression, and a somewhat effective Dedup, I could
store around 120 TB of data or more.
It all depends on whether the VTL vendor does inline or on the side
dedup, and whether they support hardware compression.  Hardware
compression is faster, and on the side dedup doesn't interfere with
backup speeds.

Another feature that a VTL can offer is post dedup replication.  I can
have a half sized VTL located at a hot site and have the data replicated
to that site for DR purposes.  No tape swapping, or offsite tape
storage, etc. etc.  And, when I rebuild the TSM server at the Hot Site
the storage pool looks just like the original so I can get started with
restores much faster.  (Or, at least that appears to be the goal of the
replication).

However, I haven't had personal experience with them, so I'm cautiously
optimistic about their worth and whether any of this actually works in a
prod system.  All, I'm asserting is that they are still worth looking
into and maybe testing with a TSM system.

See Ya'
Howard


> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf
> Of Colwell, William F.
> Sent: Wednesday, April 16, 2008 12:15 PM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: [ADSM-L] TSM being abandoned?
> 
> I have been configuring a new TSM server since last November.  At
first
> I wanted a VTL.  But when I learned from the Oxford symposium
> presentations
> that TSM would have its own dedup in version 6,
> and considering the cost of the vtl, I ditched it and ordered a lot
> more
> of SATA arrays for less money.
> 
> I think in a few years after v6 is widely installed, VTL's won't look
> so
> good
> for TSM sites.  Assuming it all works of course.
> 
> your VTL vendor may just have been whistling past the graveyard.
> 
> Bill Colwell
> 
> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf
> Of
> Paul Zarnowski
> Sent: Wednesday, April 16, 2008 12:08 PM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: TSM being abandoned?
> 
> Deduplicating VTLs fit better into NBU sites.  TSM's progressive
> incremental methodology already reduces the data stream, making
> deduping
> VTLs less of a "win", though it can still be beneficial.  My point is
> that
> VTL vendors may not look as positively on TSM as they do on other
> less-efficient backup solutions, because they don't sell as much VTL
> product to them.  IMHO.
> ..Paul
> 
> > A VTL vendor said he is seeing a number of mid-sized businesses
> > migrating from TSM to NBU (Symantec). Do you think this is true? My
> > concern is that the pool of support techs will shrink and put us in
a
> > bind.
> >
> > Regards,
> > Orin
> >
> > Orin Rehorst
> > Port of Houston
> >