Percival P. Cassidy
2011-08-30 13:12:16 UTC
I've been using BackAgain/2000 Server Edition v. 4.1 for years to do
weekly full backups and nightly differential backups to a Sony DDS4
autoloader.
The weekly backup of one of my drives starts on one tape and should
continue on the next. The log file shows, for example:
07-AUG-11 07:14:05 [id=8500] Auto-compare for volume 1 started.
07-AUG-11 07:42:59 [id=8502] Auto-compare for volume 1 completed.
07-AUG-11 08:53:28 [id=8500] Auto-compare for volume 2 started.
07-AUG-11 10:03:10 [id=8502] Auto-compare for volume 2 completed.
Yet when I try to restore files from this set, it reads the first tape,
ejects it, then starts to read the second tape and reports that the
wrong tape has been loaded. When I check the directory of that second
tape, it is either blank (in the case of a brand new tape) or contains
data from an ancient backup (in the case of a tape that was being reused).
I do recall that when BackAgain/2000 v. 4 or 4.1 was released, it was
found that with a single-tape drive the backup would simply abort if the
tape would not hold the full set; there was no prompt to insert a new
tape. When questioned, CDS replied that this behavior was introduced at
the request of a large customer to guard against data corruption (or
similar wording). I am guessing the customer had in mind the situation
where there was a long delay before inserting the continuation tape, and
the file could have changed significantly during that time. But that did
not seem to apply when the destination device was an autoloader: it just
moved on to the next tape immediately and continued backing up -- or
that is how it seemed.
So where did this "Volume 2" that took over two hours to create and
compare get written?
Perce
weekly full backups and nightly differential backups to a Sony DDS4
autoloader.
The weekly backup of one of my drives starts on one tape and should
continue on the next. The log file shows, for example:
07-AUG-11 07:14:05 [id=8500] Auto-compare for volume 1 started.
07-AUG-11 07:42:59 [id=8502] Auto-compare for volume 1 completed.
07-AUG-11 08:53:28 [id=8500] Auto-compare for volume 2 started.
07-AUG-11 10:03:10 [id=8502] Auto-compare for volume 2 completed.
Yet when I try to restore files from this set, it reads the first tape,
ejects it, then starts to read the second tape and reports that the
wrong tape has been loaded. When I check the directory of that second
tape, it is either blank (in the case of a brand new tape) or contains
data from an ancient backup (in the case of a tape that was being reused).
I do recall that when BackAgain/2000 v. 4 or 4.1 was released, it was
found that with a single-tape drive the backup would simply abort if the
tape would not hold the full set; there was no prompt to insert a new
tape. When questioned, CDS replied that this behavior was introduced at
the request of a large customer to guard against data corruption (or
similar wording). I am guessing the customer had in mind the situation
where there was a long delay before inserting the continuation tape, and
the file could have changed significantly during that time. But that did
not seem to apply when the destination device was an autoloader: it just
moved on to the next tape immediately and continued backing up -- or
that is how it seemed.
So where did this "Volume 2" that took over two hours to create and
compare get written?
Perce