I used to backup to CD-RW but then I replaced the CD Writer with a DVD
Writer and switched to using DVD-RAM for backup. At first I just changed
to backup script to use dvd+rw-format and growisofs instead of cd-record
to handle the actual disk writing. In other words, I treated the DVD-RAM
disks as DVD+RW.

I noticed however that the DVD-RAM disks weren't picking up the latest
backups. It's possible that after the initial write, they didn't allow
overwriting. Even the dvd+rw-format wouldn't erase the files.

So I decided to try actually using the DVD-RAM disks as DVD-RAM and
reworked the script to use mke2fs /dev/dvd to format (in case the user
ever puts in a new disk, it will need to be formatted, so I figured
formatting each time shouldn't be a problem). And I replaced the mkisofs
with a cp -a command (this of course required mounting the disk first).

Sometimes this works (I've only just made the changes so I haven't seen
a complete disk rotation yet). Yet in half the disks I've looked at to
verify the backup worked, I'm getting errors during the format on
sectors 0 and 2.

Warning: could not erase sector 2: Attempt to write block from
filesystem resulted in short write.
Warning: could not read block 0: Attempt to read block from filesystem
resulted in short read.
Warning: could not erase sector 0: Attempt to write block from
filesystem resulted in short read.
Warning, had trouble writing out superblocks.done

I've tried other filesystems with no luck either. mke2fs returns better
error messages than say mkdosfs -F 32 /dev/dvd. Bottom line is I can't
seem to get a good format so the subsequent mount (and copy) fails.

Any ideas?