Anne Wilson wrote:

On Monday 31 July 2006 19:45, Jon LaBadie wrote:

On Mon, Jul 31, 2006 at 06:56:22PM +0100, Anne Wilson wrote:

After the struggle to burn my tape-split backups onto DVD, I find myself
wondering just how useful they are.  The current set of backups are still
on hard drive, but what if I want to find an earlier copy of a file which
has since been burned onto DVD?

It seems to me that once vtapes are free for overwriting the
corresponding index will be lost too.  Can either amrestore or amrecover
actually access these files?

Obviously not talking from experience here.
So this is just a conceptual framework for something that might work.
You do realize that you are, or will soon be, the leading expert
on saving amanda backups on optical media, right?

Now there's a scarey thought ;-)

Suppose you had a different config for recovery (rec-config).
The rec-config might use nearly all the same config data and
could use the same curinfo/log/index directories as your
normal config.  Further, suppose you never deleted (amrmtape)
or overwrote a vtape in your regular config (unless the dvd
data were no longer needed).  That would keep the index and
log files available for amrecover.

Never overwrite a vtape? So it would be necessary to add vtapes from time to time?

Your rec-config could use a device, maybe with chg-manual,
that had "data" pointing to your dvd mount point (a symlink).

I'm not thinking well enough to recommend how to handle the
current vtapes.  Maybe rm the data a day or two before reuse,
relabel the vtape with amlabel for a new label, and maybe rename
the slot one greater than current max.


Another totally off-the-wall brainstorm; what if you reserve
one slot in your changer directory as a symbolic link to your
dvd mount point.  Say it was slot99 or slot1 or ???.  Perhaps
when amrecover asked for a particular tape you could mount
the appropriate dvd, and ammt/amtape it to the current active
changer position.

I was thinking about that from my current installation.  My
actual storage is on two external drives.  My changer "slot"
directory is on the hard system's hard drive and the "slotXX"
directories are actually symbolic links to external drive
directories.  It could just as well point to a mounted dvd
directory.

So that backup wouldn't actually write to the hard disk, but to the DVD? If it did that, tape-spanning would be problematic, wouldn't it? I can't see how it could work.

I think only for the restore not the backup.

Such an approach would be testable with your current setup.
Rename the slotXX containing the original hard disk data.
Recreate slotXX as a symbolic link to your dvd data.  Try
amrecover.

You would still need to retain index etc. and relabel hd tapes.

That's a lot to think about and experiment with. I'll play around a little when I can make time. Thanks for the ideas.

Anne