The VTL is a Sepaton S2100-ES and yes it is disk only.  

I don't see the benefit that a "tape backed" system would bring, how
does that really differ from a physical tape ATL with TSM providing a
DISKPOOL front end?

"Fewer tape-head-hours":  I understand your confusion, there was no way
to reduce the required tape-head-hours, but with a VTL if I need 30
physical tape drives then I configure the VTL as having 45 virtual
drives, more than enough.  There is no price difference for configuring
my VTL as having 1 tape drive or 64 tape drives.  

Off topic:
Configuration Based Pricing: I pray Sepaton will not start, and other
vendors will not continue, a pricing scheme based up how you configure
the software you PURCHASED.  What's next, you have to may extra to your
OS vendor for each file system you create?

Thanks,
H. Milton Johnson
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Allen S. Rout
Sent: Tuesday, June 12, 2007 3:41 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] Fw: How to Incorporate a CDL into TSM environment?

>> On Tue, 12 Jun 2007 12:16:27 -0400, "Johnson, Milton"
<milton.johnson AT CITI DOT COM> said:


> Why a VTL?  With us we found that when we out grew our physical 
> library we would have to have to buy over 30 physical drives in order 
> to be able to do backups, restores, cut off-site tapes and reclaim 
> on/off site tapes in the time allowed.  That amounted to some serious 
> money, more than our VTL costs.


I'm interested in the details on this.  The VTL is disk-only, or is it
tape backed?  I'm confused about how you need fewer tape-head-hours when
you virtualize processes.

- Allen S. Rout