More Data than Usual??

[GregE]

I setup an Oracle backup for LANfree , with dsm.sys "COMPRESSION ON" and include-exclude list as in post #7 here (excluding compression on a particular entry):
http://adsm.org/forum/showthread.php?t=19296

This was to let the tape drive do the compression:
FORMAT=ULTRIUM3C on my device class.

My backup finished in less than half the time it took when it was going to disk, BUT, when I get a daily data report, it backed up TWICE as much. 500GB vs 1010 GB.

TSM daily data used to show me about 500GB a day for this DB. Today it shows 1010 GB. Is there anything else I need to do to make the drives compress the data?? (Solaris 10. TSM server 5.4.5.0.)

 

[nezih]

if you backed up your oracle twice within 24 hour period (manual +scheduled) it's normal to see it twice...

 

[GregE]

No I only backed it up once. I think what is happening is that now that I turned off compression, to do it at the tape drive instead, TSM only knows how much data it transfers. It doesn't know what the tape drive does with it. So my 500 GB, in the eyes of TSM, is now 1010 GB.

So here's another question. I understand what TSM sees as the amount of data. But once it's compressed on tape, why do I then see double the amount of tape-to-tape copy data, if it's compressed on primary tape why does 1010 GB copy to the copy pool tape, and not just 500 GB? Is it again that TSM sees this data as 1010 GB, regardless of tape drive compression, so my tape copies now take twice as long?

 

[heada]

Tape compression turns your 500 GB tape into a 1000 GB tape. The amount of data is still the same, you can just hold more of it.

-Aaron