[plug] Backups

[Craig Ringer]

On Wed, 2004-07-28 at 09:03, Marc Wiriadisastra wrote:

> If I want to use dump the weekly full file system I would use dump  -0 
> (number 0) for a full filesystem and then for the incremental just make 
> the daily backups dump -1 so those are incremental.

No idea, sorry.

[snip]

> Also because I'm unsure about size. I wanted to compress it to my 
> harddrive then use a cron job to transfer to the dvd drive when I'm at work.

File size issues are something you'll have to deal with no matter what
backup method you're using (well, unless you're streaming directly to
tape).

> Yes it is dvd +- R/ +- RW so I can use read writable media, which is 
> what I was planning to do mainly for cost savings.

I thought DVD-RW was only rewritable after an erase pass, but generally
behaves much the same as a CD-R or DVD-R - you write an image, and
that's it. If so, while useful this is not what I was taking about when
I said 'randomly rewritable'. Randomly rewritable media like hard disks
can seek to any location and overwrite just that location without
affecting anything else (they can also usually do this reasonably
quickly). Basically, you need randomly rewritable media to be able to
put a normal filesystem on, and I didn't think DVD-RW qualified.

IFAIK DVD+RW /is/ randomly rewritable, but I don't know what the driver
and filesystem support for that is like under Linux, and it has some
limitations that would make me reluctant to use it.

> I had errors before which I tried to tar.gz a group of files for max 
> 2gig file size limit or something. 

Odd - that should only be happening with very old distros and kernels.
Could you have been saving the tar file to a different filesystem (say,
fat32)?

> Is that a logical method to backup stuff or am I like off target or am I 
> missing something.

Omitting the specifics about dump, because I don't know enough to say,
it seems reasonable. You'll probably need to find a way to prevent dump
from trying to dump the dump file you're creating on the hard drive,
though. You'll also need to think about how you're going to write the
dump file to CD - you'll probably want to include it in an ISO9660 or
UDF image with mkisofs or a similar tool. It might be possible to write
the dump image onto the DVD without a filesystem, using the DVD much
like one would tape media. I haven't tested this though, and don't know
what potential issues might be encountered.

--
Craig Ringer