I never said 32 drives. In fact, they routinely defined 48 drives per
library, although I don't think they ever had that many in use. Larger
numbers let more large clients (databases, mostly) use more streams
(drives) concurrently, but at some point, the SAN becomes a limiting
factor, if the client CPU doesn't choke first.

If we were to do it over again, we'd have defined fewer drives per library
and had fewer DataDomains with more capacity for each. We were worried
about over-taxing the I/O of those appliances, but that never became an
issue. I'm not saying it didn't happen, but if it did, there were enough
other factors that we never blamed it on I/O capacity.

On Mon, Sep 15, 2014 at 1:51 PM, Saravanan <evergreen.sarav AT gmail DOT com>
wrote:

> Thanks for your response ,
>
> Why 32 drives ?
>
> Yes VTL can write 10 TB/ hr without DD Boost
>
> I may not start with 32 but still need to calculate total number of
> servers , any time constraint and database size to decide the count
>