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No backup compression achieved

Ian W Roberts
Occasional Visitor

No backup compression achieved

I have a tandem pair of 12/24 GB HP SureStire DDS-3 drives that ought to be able to back up the entire file system on my Windows NT/Lotus Domino server provided that:

1. Compression is enabled
2. A reasonable level of compression is achieved

Unfortunately I'm running out of capacity with my backup software (CAI's Arcserve with CAI's Open File Agent for Lotus Notes) reporting "media full" after backing up data just about exactly equivalent to the native capacity of the DDS-3 DAT tape drives, ie I can see no evidence of any compression at all.

HP's tape drive analysis utility reports that hardware compression is enable and functioning correctly. The ArcServe software is configured to enable hardware compression (and when so enabled correctly prevents software compression).

There appears to be no reason to assume that Lotus Notes databases are not compressible (a test with PKZIP achieves a 2:1 compression ratio). I presume that both PKZIP and the drive hardware implement similar (but not identical) LZ compression algorithms.

Any suggestions? Is the Lotus Notes OFA preventing compression?

I'm running ArcServe Backup v6.61 build 834 and Lotus Notes Open File Agent v6.61 build 105 on a Windows NT/Lotus Notes/Domino server.
2 REPLIES
Michael Tully
Honored Contributor

Re: No backup compression achieved

Have you tried to utilise software compression instead of hardware compression?
From my experience, software compression will get a better compression ratio generally than hardware.
If files are already zipped, you won't get much of a benefit whether you utilise software or hardware compression.
Anyone for a Mutiny ?
Eugeny Brychkov
Honored Contributor

Re: No backup compression achieved

Ian,
please make sure that only one compression is turned on - either software or hardware.
Try new (just unpacked) HP DDS3 tape.
Attach support ticket generated by HP LTT from http://www.hp.com/cposupport/information_storage/support_doc/lpg50128.html to your next reply. This utility has compression test (uses specially designed for tests data), and if it shows that drive's compression is ok then there's a problem with Arcserve compression or Lotus data could not be compressed
Eugeny