> 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.  

As I've said before, TSM's progressive incremental does tend to reduce
the total dedupe ratio by about 50% (from an average of 20:1 to 10:1).
There is still plenty of duplicate data between the multiple versions of
each file you're saving in TSM, and TDP backups stil do fulls and
incrementals.

> 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.

This is DEFINITELY not the case, as most VTL vendors that I've talked to
are selling a disproportionate amount of VTLs on TSM.  In fact, I'm
seeing more customers than I thought I would abandoning their disk pool
and going straight to VTL.  

When we start talking dedupe, though, the numbers do go way down,
though.  There's no doubt it brings a benefit to the TSM customer, but
the pricing is such that some TSM customers feel they're being
overcharged.  If dedupe makes my 1 TB array look like a 10 TB array
(10:1 dedupe, common with TSM), and you want to charge me a 10x multiple
for it, what's the point in that?  (I'm not saying that's how the
vendors are pricing it.  I'm just giving an example of the type of
pricing that might turn off a TSM customer.)

---
W. Curtis Preston
Backup Blog @ www.backupcentral.com
VP Data Protection, GlassHouse Technologies 





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