Cannot mount DVD-R produced by cdrecord

cfgauss · 09-01-2007, 12:50 AM

As part of a backup of my home directory I recorded to a DVD-R with dar

Code:

dar -v -c "/var/backups/dar-backups/home-foo-full" -R "/home/foo/" -w -s 4613734400 -p
-D -y -m 150 -Z "*.bz2" -Z "*.gz" -Z "*.jpg" -Z "*.tbz" -Z "*.tgz" -Z "*.zip" -E "cdrecord -sao
 -eject dev=/dev/hdc %p/%b.%n.%e" -X "*.dar" -X "*~" -X ".*~" -G "/var/backups/dar-backups/home-foo-full-cat"
rm /var/backups/dar-backups/home-foo-full.1.dar

The recording to the DVD-R seemed to go OK--the light on the device was lit and cdrecord gave these messages:

Code:

Starting to write CD/DVD at speed 4 in real SAO mode for single session.
Last chance to quit, starting real write    0 seconds. Operation starts.
Track 01: Total bytes read/written: 315970838/315971584 (154283 sectors).

Now I'd like to restore some files but I can't mount the DVD-R as root.

Code:

gauss:~# mount /mnt/cdrw
mount: block device /dev/hdc is write-protected, mounting read-only
mount: you must specify the filesystem type

/etc/fstab has the line

Code:

/dev/hdc /mnt/cdrw auto noauto,user,rw 0 0

I then tried

Code:

gauss:~# mount -t iso9660 /dev/hdc /mnt/cdrw
mount: block device /dev/hdc is write-protected, mounting read-only
mount: wrong fs type, bad option, bad superblock on /dev/hdc,
       missing codepage or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

Does anyone know how I can access the file home-foo-full.1.dar on the DVD-R?

Thanks.

kotnik · 09-01-2007, 05:51 PM

What was the cdrecord line you used to record dar file?

cfgauss · 09-01-2007, 05:56 PM

Quote:

Originally Posted by kotnik

What was the cdrecord line you used to record dar file?

The dar flag is

Code:

-E "cdrecord -sao -eject dev=/dev/hdc %p/%b.%n.%e"

which, when the dar variables %p, %b, %n, and %e expand, becomes

Code:

cdrecord -sao -eject dev=/dev/hdc /var/backups/dar-backups/home-foo-full.1.dar

kotnik · 09-01-2007, 05:59 PM

Well, you didn't use any filesystem on your DVD, so file was being directly burned.

You can't mount this DVD. There is no dar filesystem. If you want it, then get it:

cp /dev/hdc $HOME/backup-whatever.dar

Under Unix, everything is a file.

cfgauss · 09-01-2007, 06:25 PM

Quote:

Originally Posted by kotnik

You can't mount this DVD. There is no dar filesystem. If you want it, then get it:

cp /dev/hdc $HOME/backup-whatever.dar

This helped immensely. But dar can't seem to read the file created.

Code:

# file *
home-foo-full.1.dar: dar archive, label "95e33c46 00000000 2a59" end slice
# dar -l home-foo-full
FATAL error, aborting operation
Reached end of file before all data could be read

Is there any way I can get dar to read this file so that I can restore from my backup?

Thanks.

osor · 09-01-2007, 09:33 PM

Perhaps try reading the raw bytes from the DVD? For example, try

Code:

dd if=/dev/hdc of=$HOME/backup-whatever.dar bs=315971584

That number (315971584) came from your original post, detailing how many bytes were written to the disk in the first place.

cfgauss · 09-24-2007, 06:08 PM

I wasn't able to get the bytes off the backup DVD-R. I've changed my backup strategy to use mkisofs and have had no problems restoring from a CD-RW or DVD-R on which I've use mkisofs first.

Thanks for all the suggestions.