Hi Paul,

I haven't installed 6.2 yet so I haven't tested client side dedup (CSD).
But I don't think
I would apply it to PST files anyway.  CSD doesn't solve the problem of
chunk expiration.
But if the network folk told me the network was overloaded and could
prove that backups were
the problem, then yes I would try CSD.

6 years ago Draper Lab was using Eudora for an email client.  Eudora
detached attachments
to a folder where they were backed up once; backups of email were not a
problem for TSM.
But then we wanted to get into calendaring.  So we tried the Oracle
Collaboration Suite
which required outlook as a client.  So everyone's Eudora folders were
sucked into PST files.
Since our users are not restricted about how much email to keep, they
kept pretty much
every email and still do.  The result was huge PST files; there are
100's of PST files 
larger than 10 GB.

Of course there was no planning for backing up the new PST files;  I had
to scramble.  I
directed them to a separate storage hierarchy and changed the policy
from 10-90-5-180 to 3-7-5-180
to expire them much quicker.  This made for a pool of tapes which rolled
over
quicker so I could keep my media expenses under control.  My current
policy on v6 is very similar.

Well, the OCS was a failure so in came Exchange about 5 years ago.

My idea of the best way to deal with PST files is to ban them entirely.
Instead have unlimited
quotas in Exchange and deploy an exchange backend archiving product to
keep the exchange db
manageable.  Some of the mail managers think this is a good idea too,
but we are now in the
midst of a drawn out exchange 2010 implementation so there are no
resources to get serious
about an archiving backend.

Thanks,

- bill



-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Paul Zarnowski
Sent: Tuesday, November 16, 2010 1:42 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: De-dup ratio's

By using source-mode deduplication, you could avoid backing up the
entire PST files every day.  We've just introduced Exchange here, within
the last year, and are still figuring out the best way to deal with PST
files.

At 10:51 AM 11/16/2010, Colwell, William F. wrote:
>But I won't start deduping PST's again because they are backed up every
>day and I only keep 3 versions
>so why do all the dedup effort only to have to go thru the chunk
>deletion effort 3 days later?
>Then I would have to reclaim the volumes to actually get the space
back.


--
Paul Zarnowski                            Ph: 607-255-4757
Manager, Storage Services                 Fx: 607-255-8521
719 Rhodes Hall, Ithaca, NY 14853-3801    Em: psz1 AT cornell DOT edu