Hello all

Is anyone who uses CRCDATA on tape pools willing to share their experiences
with us?

I'm looking at using it to improve data integrity, by periodically running
AUDIT VOL on a random selection of volumes. I have some thoughts, but
nothing beats real experience:

- How do you choose which vols to audit (do you pick N per week, M% of all
tapes produced, or what?)
- How do you audit offsite vols? (If they have data on them, you have to
first recall them, but then there are issues like you're not covered while
you have both copies onsite. But if you wait until they're reclaimed and
returned onsite for scratch, you can't use AUDIT VOL because they don't
contain any TSM data.)

- Have you measured the performance impact? IBM estimate 5% CPU overhead.
Is this correct? Is this the only overhead - what about tape performance?
- Does it have any issues with large files (eg 6+ GB Oracle DB files)?
- Does it give you anything that the tape-drive's builtin error correction
doesn't?

- And of course the 64,000 krone/pound/dollar/euro question: Have you ever
caught an error by using CRC? Ie, is it worth the effort?

Richard Foster
Norsk Hydro asa

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