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[Networker] Legato Issues
2005-09-01 10:14:57
Imagine I'm backing up a machine. The backup is taking place as part
of an autostarted group. The pool that is selected on the basis of
the hostname, group and level is disk based. When the group
completes, an incremental backup is taken of the indexes, which goes
to tape. We now have the savesets on disk, with their indexes on tape.
At some later point, either based on the age of the saveset or the
capacity of the disk volume, the savesets are staged to tape. The
savesets that end up on tape have the same ssid as those that
originally went to disk, and therefore reference the same items in
the indexes, which has gone to tape. However, only the media
database will know that the savesets are now on tape. By
observation, no metadata goes to tape at this point. The clones that
were on disk are then deleted.
So the timeline is:
Perform backup to disk.
Write indexes to tape.
Write savesets to tape.
Delete savesets from disk.
What would happen if my media database were to be damaged after the
savesets have been deleted from disk? The only thing that knows that
the savesets are on tape is the media database, and I only have one
copy of that. Which just got destroyed. The only way to find those
savesets again is to get the ssid from the copy of the media database
which was written to tape after the original save to disk, and then
trawl through all the media that could possibly have been near a tape
drive in the intervening period looking for savesets.
I think that the media database should be backed up to tape after the
savesets have moved from disk to tape, but before they are deleted
from their source device.
Or am I missing something?
ian
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