That depends -- is the data already compressed, or is the drive doing
the compression on-the-fly? And are these small files or large? In our
environment (ADSM storage pool on SSA drives - but not raid) with the
'small' files in the 20 to 40 MB range, and the drive doing on-the-fly
compression (averaging about 2.5 to 1) we were getting up to 7 MB/sec.
The usual speed was in the 4.4 to 4.7 MB/sec, and it was SSA drive
limited. I'm not sure about the transfer rate on SSA raid - SSA *loop*
performance is very good, but individual SSA *drives* don't perform
quite as well as the equivalent SCSI drives.

Tom Kauffman
Sr. Technical Analyst
NIBCO, Inc.

>----------
>From:  Kelly J. Lipp[SMTP:lipp AT STORSOL DOT COM]
>Sent:  Friday, November 14, 1997 1:46 PM
>To:    ADSM-L AT VM.MARIST DOT EDU
>Subject:       3590 Tape Performance
>
>Anyone:
>
>What sort of data rates are you seeing writing information from AIX RS6000 to
>3590 tape drives?
>
>Is 3 MB/Sec a reasonable expectation?  I'm writing from an SSA RAID array.
>
>Thanks,
>
>Kelly
>