[PLUG] Backing up to DVD?

[Steve Bonds]

On Tue, 2 Dec 2003, Chris Jantzen chris-plug-at-maybe.net |PDX Linux| wrote:

> On Tue, Dec 02, 2003 at 05:51:24PM -0800, Steve Bonds wrote:

> Why does everyone keep recommending dump?

"everyone" is probably mostly me.  ;-)

> It's very fs-specific and I seem to recall even ext2 maintainers
> deprecating it although I could be wrong.

It's not deprecated:

http://dump.sourceforge.net/isdumpdeprecated.html

> It seems a very fragile format to back up to.

I don't find dump fragile at all, particularly on Linux where the dump
source is readily available should I need to restore some antique CD-R 20
years from now.  Once you throw in compression, I feel that all backup
methods are pretty fragile.  This can be mitigated by using reliable media
and periodically checking the backups to see if they can be restored.

I use dump since I like the bashlike shell available in "restore -i".  It
also handles incrementals, compression, and multi-part archives easier (in
my opinion) than "tar".

W. Curtis Preston, author of the O'Reilly "UNIX Backup and Recovery" book
also recommends "dump" since it's easy to get backups done correctly with
it.  From his chapter on Native Backup and Recovery Utilities:

-----
This chapter describes the benefits and pitfalls of several utilities.
dump and restore are usually the best option if they are available. After
dump and restore, cpio has the best functionality, but it is slightly less
user friendly than its cousin tar. tar is incredibly easy to use and is
much more portable than either dump or cpio. If you have to back up raw
devices or perform remote backups with tar or cpio, dd will be your new
best friend.
-----

I never would have started using "dump" if it weren't for this book.  One
tour of a partial recovery with "restore -i" was enough for me to become a
dump believer, particularly after all the failed or partial "tar" restores
I'd done because of a misspelled or forgotten file.  Guess what?  You get
to read that whole tape all over again.  Grrr.

With "restore -i", I would just "cd" into the directory I wanted to
restore, pick the files I wanted, and go.  (Though I admit that I often
had problems restoring multi-part dumps until I started using the sleazy
"-a" flag on the restore.)

Other things I like about dump:
  + it's almost impossible to forget to include some of the
    files/directories on a filesystem
  + built-in gzip/bzip compression, and you can choose the multi-part file
    size after compression (-M -B)
  + strange files/devices/fifos/etc "just work"
  + really easy incrementals

Things I don't like about dump:
  + it's almost impossible to selectively exclude files/directories
  + on heavily written filesystems it's easier to get skipped or
    partially-backed up files than with tar/cpio. ("restore -C" will find
    this out for you)
  + it's really only useful for backups, whereas tar/cpio are useful for
    copying files, making archives, sending a file collection to someone,
    etc.

The most important thing is to DO the backups.  The method you use to get
there is far, far less important.  ;-)

  -- Steve