On Tue, Apr 20, 2010 at 19:34, CRPence <CRPbottle@xxxxxxxxx> wrote:
 Does the noted "Verify" feature support serial media? ÂI would be
surprised if it did.
It does. And it's simple to implement in something like BackupExec (or
BRMS, for that matter). While streaming the data to the tape drive,
the data is hashed (using e.G. a SHA1 checksum). After completion of
the backup, the backup set is read back to memory, sequentially hashed
and discarded (thus needing not much memory or disk space). If the
checksum read back matches what was written you can be pretty sure
that you have on your tape what the backup program intended to write.
Note that this strictly isn't necessary on LTO drives, as those
already do verify-after-write, internally.
Of course, this checksum doesn't guarantee restorability. I think it's
much more important to do tests of restores. For example, i test a
full restore of one of our production systems on a test system every
month. Since we have an HMC, i can do this from almost anywhere as
long as the UMTS modem in my laptop connects. Most of the time in a
restore is spent waiting anyway.
midrange.com
