On 2011-09-21 15:20, George Sinclair wrote:

On 2011-09-21 14:54, bingo wrote:

To answer your questions:

1. Even if the index does not get updated because the pool doesn't have
the "Store index entries" turned on, what would happen if the group did
*NOT* have "no index save" checked? Obviously, nothing would have
changed in the index, thus no backup of the index to tape, but lets say
isntead that a full was being run, and not an incremental. Would NW send
a copy of the index to tape in that case even though no change was
affected on it?

You are right - these are different issues. The index backup is run
via a savegrp command while the index is generated (or not) for any
backup, automatic or manual. It just depends to which pool the data
will be sent.

A differential index backup considers any change of the index of that
client. As as there changed nothing when the index has not been
updated, nothing can and will be backed up.


2. I'm unclear on why indexing being turned off for the pool would
preclude you from scanning the tape and adding that information to the
index? Is it the case that if the data was never indexed before then you
can't add it to the index later? Or are you instead referring to using
scanner to recover an index that was never written to tape? That
obviously would not be possible since it was never sent to tape.

The default option 'Store index entries' actually has 2 tasks:
- it generates the CFI metadata and embeds it within the save stream
already at the client.
- it send this info to the CFI at the server in real time.

By disabling it, you already switch of the CFI info generation - it is
logical that there will be nothing to retrieve when you run 'scanner'
later. Try it yourself.

What you say makes perfect sense now that I think about it. After all,
how can you recreate index metadata information if you can't determine
what that should be? And having the file(s) on tape doesn't give you
that. Yes, you have the file(s), but what about the user, group,
permissions, etc? All of that original metadata would have to be saved
to the tape, too, which it would not be with the 'Store index entries'
disabled for the pool.

BUT could NW determine at least the names from the data as it scans the
tape and then build/update the index that would at least have those file
names? Or is it the case that it can't determine the names from the data
on the tape and depends solely on that CFI information having been
written to the tape?

If indexing is turned off for a pool, and some of the media database
entries are later removed, you can still scan the tapes and rebuild the
media database entries for those save set sets, but you can't re-create
the index entries. Correct?

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George Sinclair
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