"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> wrote on 06/28/2007
01:02:27 PM:
> The compression algorithms in tape drive hardware are usually the
> best, and though will attempt compression per your settings, the data
> will not expand as in some host software compression algorithms.

A long time ago we used AIT1 tape drives.
AIT1 drives used a IBM compression
chip.  I was able to find a document for that chip that described
many of it's operations.  It stated that if data was uncompressable,
the data was passed through as-is.  In other words, it handled
the case of trying to compress a already compressed data stream.

Since then, I haven't worried about this issue, reguardless
of the type of drive.  We let the
drives compress regardless of what we send - and we do send a
broad mix of compressed and uncompressed data.

Rick


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