[Digikam-users] Re: Back-ups on CD/DVD with DAR (was Re: On backing up)

[Dr. Martin Senftleben]

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Hi,

Am 24.02.2011 18:51, schrieb Johnny:
> "Dr. Martin Senftleben" <drmartinus at drmartinus.de> writes:
> 
>> I use dar, however not with CDs/DVDs
> Great to hear an acutal user, could you please review it's advantages a
> bit more, as you're not using space restricted media? 

I also use slices, but it wouldn't be necessary. They are all 4 GB in
size. I have quite a long config file in which I note down which paths
and file(-types) to exclude and what compression it should use. I
figured out that there is a big difference in speed when using
compression on already compressed files, so I excluded also quite a few
file types from compression. It's a good thing that dar has these
options. Among them are most of the photos. Still, if I do a full
backup, it takes about 24 hours. However, i can change the priority of
dar, then it's a bit faster.

>> that would require an awful lot of disks (the initial backup requires
>> about 1 TB of space).
> I agree and have not yet estimated number of disks I would need... OK, I
> use only 100 GB so far, so only.... 20 DVDs roughly! Yes, it is quite a
> lot, but I like the idea of having a third backup in a non-erasable
> media, as after all, any hard disks can be overwritten accidentally
> (however I would agree it is unlikely to happen simultaneously, but
> assume one would fiddle up the back-up script, so when backing up,
> actually both locations are overwritten? SPOF.)

Well, i have of course checked my backup script for any possible faults.
I think it's safe, I hadn't had any problems and use it already for a
few years. I take the hard drives out of the fire proof box only for the
backup, so there is no danger of mixing it up and doing the wrong thing.
And dar warns you, if anything happens like attempt of overwriting the
existing archive or other such things.
The backup is done with an automatically attached date in the archive's
filename, which works just fine. The archives have filenames which make
it impossible to overwrite the original data. They are just different.
So if someone fiddles with the script, then the only thing that could
happen is that the archive is placed on your hard drive in the PC, and
not on the external one. Unless, that someone gives a name for the
archive file that exists on the hard drive already. But then, dar will
prompt you for input on what to do - whether overwrite, abort or I don't
know what else ;-).

>> I attach eSATA disks to the PC ...
> What in your opinion do you achieve that cannot be done with rsync by
> using dar in this way?

no idea. I don't trust rsync the way I trust dar, because I always fear
that rsync, as it syncs files, might overwrite the wrong files... I
really haven't worked much with rsync.

Hope that helps

Martin
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