Being that TSM does incremental, your de-dupe ratio will be lower than
other Full / Incr backup products.  Here's a few lessons learned with TSM
and a Diligent Protectier.

        1) Do the best you can to put like data together. (ie all Oracle
DB Backups go to the same de-dupe VirtualTape head (Repository),

        2) Turn off all compression (Client and DB's)

        3) Oracle Specific
                Do not use RMAN's Multiplexing in RMAN will combine 4
Channels together and the backup data then will be unique every time thus
not allowing for                        de-duping)
                Use the File Seq=1 (Then run multiple channels)

        4) Do not Mix Windows and Unix data, It wont de-dupe well.

We are seeing 10 and 15:1 on our Oracle and DB2, Exchange 12:1 (The DB's
and Exchange all do Daily Full Backups)  In the regular Win env, we see
1.45 and 2:1 ick...

Hope this helps.

Regards,

Charles





Dirk Kastens <Dirk.Kastens AT UNI-OSNABRUECK DOT DE>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
08/27/2007 02:31 AM
Please respond to
"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>


To
ADSM-L AT VM.MARIST DOT EDU
cc

Subject
Re: [ADSM-L] Data Deduplication






Hi,

> Writing a de-dupe backup product isn't easy.  EMC bought Avamar and
> Symantec bought Data Center Technologies to get their respective
> products. I don't know of any other de-dupe companies for IBM to
> acquire, so they'll have to write their own.  That may take them a bit
> longer.

We're just testing a deduplication disk array from DataDomain with TSM.
The compression ratio is much less than promised by the sales people.
During the last 10 days of incremental backups we only achieved a ratio
of 2.6:1. The disk array is very expensive and for the money you can buy
more disks than you need without compression.

--
Regards,

Dirk Kastens
Universitaet Osnabrueck, Rechenzentrum (Computer Center)
Albrechtstr. 28, 49069 Osnabrueck, Germany
Tel.: +49-541-969-2347, FAX: -2470



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