[ILUG] Alternative filesystems on a DVD

[Malcolm Tyrrell]

Thanks for the various replies so far:

I'll reiterate my worry:
* CDs/DVDs are likely to fail in a different way to hard disks.
* It's possible that iso9660 is designed to reduce the risk of curruption due
to the kind of failures that CDs/DVDs are vulnerable to.
* It's possible that ext3 is designed to reduce the risk of curruption due
to the kind of failures that hard disks are vulnerable to.
 
If this is true, then shouldn't I be a little worried about trusting my back-ups
to ext3?

Glenn Strong wrote:
> No real problems (modulo the usual questions as to whether DVD/CDR
> media count as long term)

Good point. I wouldn't trust a DVD back-up for too many years, anyway.

Colm MacCarthaigh wrote:
> I certainly wouldn't want to bet on it being easy in 10 years time to read a
> current ext3 filesystem. 

Also a good point. But that's longer term than necessary.

> Or do you want something you can more easily restore individual files from?

That's definitely a feature for me.

Daniel Shaw wrote:
> Create a loopback filesystem within a 4 gig blank file...

Yep. Here's what I did to create the ext3 DVD:

touch imagefile
dd if=/dev/zero of=imagefile bs=2048 count=2200000
/sbin/mkfs.ext3 -b 2048 imagefile
mount imagefile /mnt/mountpoint -t ext3 -o loop
...copy files into /mnt/mountpoint...
umount /mnt/mountpoint
growisofs -Z /dev/dvdrw=imagefile

I guessed the size of the file (2,200,000 * 2,048 = 4,505,600,000) because
I couldn't remember exactly how much a DVD can hold. The answer is
4,700,000,000 bytes apparantly.

Good luck,

Malcolm.