[SLUG] Backup

[Paul Teasdale]

> john at johnallsopp.co.uk wrote:
>> I'm moaning, as usual, about Linux usability.
>
> This wasn't a new year's resolution then? :P
>
>> What's a backup
>> system if it doesn't write to backup media?
>
> Well that depends on what you call "backup media" - typically people use
> tape drives and I wouldn't mind betting that linux supports writing to
> them in the kernel. I would be surprised if "windows backup" writes
> straight to dvd, and if it does it almost certainly won't have done
> until some relatively recent service pack... but yes, I know that "they
> don't excel in this so why should we" is hardly a compelling argument.
>
Back in the days of Windows 95 I played around with a technology call
Packet Writing. I installed a piece of software called Adaptec DirectCD (I
think) that ran as a background process. When you inserted a blank CD-R or
CD-RW it popped up a dialog asking if you wanted the format the disk with
a UDF filesystem. After doing this you could drag and drop files from your
hard drive to the CD drive transparently (i.e. you did not need to master
the CD image first).

This got me thinking after reading your thread. Can Linux do this? It
appears that from kernel 2.6.10 packet writing is part of the kernel.
Before 2.6.10 you could install it as a kernel patch.

So it may be possible to investigate this path. You will most certainly
need to ignore this patch but read the description that explains what
packet writing is especially the second paragraph:

http://packet-cd.sourceforge.net/

Here is a link to a packet writing howto but it's Gentoo specific. You may
be able to find a Fedora howto.

http://gentoo-wiki.com/HOWTO_Packet_Writing_on_CD-RW

I have never tried packet writing under Linux but the basic gist is:

1) Ensure packet writing is complied as a kernel module. Fedora will have
probably already done this for you and if they have not then I would guess
it's problematic.

2) Ensure that kernel module is loaded. This probably will need to be done
as I think it very unlikely that it's loaded as default. Tip: Use modprobe
to get it going temporarily just for experimentation purposes.

3) Ensure the UDF tools are installed. (Sorry I don't know the Fedora
package so you will need to investigate).

Now for each disk you want to use you will probably need to format it as a
UDF file system. You should then be able to mount the disk and copy files
to it via a script (or manually) without the need for mkisofs and cdrecord
(hopefully). You will probably need to mount the disk using the UDF file
system and not the iso9660 they are normally mounted as (e.g. mount -t udf
/dev/??? /mount_point). Also beware that LVM may give you some grief as it
appears to be doing now.

I also remember (this may not be true now) but with a CD-RW it just kept
filling even if you deleted files from it. If you wanted to re-use it you
had to re-format it. (Note: Obvisouly CD-Rs just kept filling anyhow
because as you know they are write once).

In short it could be a pain to get going but may pay off in the long run.

Hope this helps.

Regards,
Paul.