Storing Data on DVD

NOTE: Nested subdirectories are now supported by the writing script.

Important information about the DVD backup system.

  1. We have TEAC DVD+RW drives and recommend observers bring DVD+R (not DVD+RW) disks to avoid the possibility of overwriting observation data.

Backing up data to DVD.

There is a script in /home/obs/bin/dvdw_dir.pl which an observer can use to write a directory to DVD. It will automatically break a large directory into DVD size chunks and prompt the user for input of new DVDs

To use dvdw_dir.pl:

    /home/obs/bin/dvdw_dir.pl full_path_of_your_data_directory

The script will calculate the size of the directory and how many disks required and then prompt you to insert a blank DVD.

    Checking size of /data/m42i
    Writing 10529500 Kbytes onto 3 DVDs
    Ready to write 767 files to DVD 1
    Insert new DVD disk into drive and press enter after 'burn' window appears:
    Enter 's' to skip, and 'q' to quit

After inserting the disk wait for the nautilus burn utility to appear before pressing enter. This is a workaround for the fact that it takes quite a few seconds for the DVD to be initialised in disk. If you press enter too soon the DVD will not be written but report an error and go on to the next DVD. The script will be fixed to detect the presence and report to the user in the near future. By pressing 's' you can skip the current DVD, and go on to the next DVD volume. This is useful in case a previous attempt to backup was interrupted at volume 3, e.g., and you don't want to rewrite DVDs 1 and 2, since you already have those backed up. If the directory hasn't changed since your last back-up, DVD 3 will end up having the same files on it that it would have had on it during the first back-up attempt.

What to do if one or more disks fails to write?

dvdw_dir.pl writes listinging files in the current directory these are named listN.out where N is the disk number, starting at 1. To write a disk manually after dvdw_dir.pl has completed do the following:

    /usr/bin/growisofs -Z /dev/scd0 -l -R -path-list listN.out

What to do if one or more disks is writing very slowly?
Normally a 4.2 Gbytes DVD disk should be finished in about half an hour. If your DVD writing is going much slower than that, e.g., it anticipates taking more than 2 hours for 1 DVD, then you can try the following:

su - root
cd /proc/ide/hdd
cat settings
Look for "using_dma" (at the bottom of the list of settings), and check that the value is 1. If it's not, then you need to set it to 1. If you're *NOT* writing a DVD at the time, just do:

/sbin/hdparm -d1 /dev/hdd

If you are in the middle of writing of a DVD and you don't want to wait forever for it to finish, and would rather not interrupt the writing, then do this:

click on the window in which you are writing the DVD (i.e., in which you started the dvdw_dir.pl script)
press CTRL-Z
in a different window, as root, do: /sbin/hdparm -d1 /dev/hdd
in the script window, do: fg

The writing should now go faster. Suspending the job is important (CTRL-Z), otherwise the writing will crash. The "using_dma" switch is sometimes switched off if there was a problem with writing a DVD, so it's not a bad idea to check for it after such an event.

Time-stamp: <2004-04-14 10:24:26 dettori>
Peter Dettori <dettori@astro.su.se>