# Backup to DVD

## amasidlover

I've got myself a NEC 1300A DVD writer - they're so cheap now I couldn't believe it - for doing backups. The first backups work fine however now I'm back through my seven day cycle I get a problem overwriting the disk.

If I run from the command line I get this:

```
growisofs -Z /dev/sr0=/usr/download/tmp/image1.img

WARNING: /dev/sr0 already carries isofs!

About to execute 'builtin_dd if=/usr/download/tmp/image1.img of=/dev/sr0 obs=32k seek=0'

         0/1073891328 ( 0.0%) @0x, remaining ??:??

         0/1073891328 ( 0.0%) @0x, remaining ??:??

  17432576/1073891328 ( 1.6%) @3.7x, remaining 10:06

  42827776/1073891328 ( 4.0%) @5.4x, remaining 5:12
```

And everything works fine.

However if I run it as part of an overnight backup script with cron then I get this:

```
FATAL: /dev/sr0 already carries isofs!
```

In command line mode it waits 5 seconds to allow me to cancel, presumabley when it runs from cron it knows that I can't cancel it and hence aborts. Is there a way of forcing it to work using a command line option?

I thought about going for the builtin_dd program directly but I can't seem to find it so I assume it must be internal to growisofs.

Thanks for any help,

Alex [/code]

----------

## Robelix

Use growisofs -Z to write the first time to the dvd.

To add something: growisofs -M.

Wipe a disc with dvd+rw-format, then you can start again with growisofs -Z.

Works fine with my LG +- Drive.

Roland

----------

## amasidlover

Actually I solved this one some time ago but forgot to post a reply. Doing regulat dvd+rw-formats is bad for the disc, the correct solution is to add the comand line option -use-the-force-luke (for growisofs) which is undocumented except in the source code.

----------

## juhajuhajuha

Thanks, I just stumbled upon the same problem and right away there was an answer. Technical problem solved, but the more theoretical one persists: there seems to be some law of nature that says backups are always slightly larger than the size of a recordable optical disc.

----------

