Re: [PLUG] Best Solution for Multiple Volume Backups

[Rich Freeman via plug <plug@lists.phillylinux.org>]

On Sun, Jul 19, 2020 at 10:52 AM Steve Litt via plug
<plug@lists.phillylinux.org> wrote:
>
> I hadn't thought of this until you brought it up, but how bout
> something like the following:
>
> tar -Mczf --exclude=pattern /mnt/flashdrive /backuptree

Yeah, tar definitely has this capability, but I have a few concerns with this:

1.  If for whatever reason I want to extract 1 random file I shudder
at the thought of sequentially scanning many TB of backups and all
incrementals.  Tar lacks any kind of indexing.
2.  While I haven't played with it, in theory bacula supports
pause/resume which means that if I'm in the middle of a week-long
backup and need to reboot there is at least a prayer it can be done,
and I'm guessing an incremental will pick up whatever got missed.
3.  Bacula has a lot more options around ensuring incremental backups
are complete.  I think the default is using ctime/mtime/date, but you
can go as far as to use hashes (which necessitate reading every file
in the set of files to backup, so incrementals will be very slow, but
very complete).  I'm not sure if tar is as capable.

Bacula is definitely cumbersome, but when it comes to multi-TB backups
it seems more like the right tool for the job.

If I were just dealing with a few hundred GB I'd be more inclined to use tar.

Dar is another option - it is basically a tar-like utility that is
designed for disks (ie where random seeks are allowed).  It does the
common approach of sticking an index at the end of the archive file,
so instead of sequentially scanning the file to find out what is in it
the utility can just seek to the end and read the index, which has no
cost on disk but very high cost on tape.  I think it does support
multi-volume operation.  However, again I'm not sure it is really the
right tool when you're talking about multiple TB backups.

-- 
Rich

-- 
Rich
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