On Mon, May 03, 2004 at 10:45:26AM -0400, Jonathan Dill wrote:
> Which reminds me...If cost is a factor, now that FILE-DRIVER is an
> option, RAID or removable hard drives may give you a better $/GB ratio
> than tapes, and much more capacity than CD-R.  I think this is a very
> good option for a single computer or small network like Justin described
> in his original e-mail.  If you use removable drives or a RAID-1, you
> might not need anything else, though it would be a good idea to still
> dump more important files to tape or writable DVD media occasionally.  I
> haven't investigated it, but I have heard of hot-swap external SATA and
> firewire options which would be very good indeed.
> 
> 250 GB removable drives could be a great option if you are backing up
> large partitions, say up to 500 GB uncompressed, so that you could get
> around dumps not fitting on a single tape without having to use RAIT
> with multiple tape drives, or very expensive tape drives and media, or
> split up dumps with (IMHO inefficient and CPU/IO intensive) GNUTAR.
> 
> In my case, I am using a 1 TB Snap Server 4500 in a RAID-5 configuration
> and flushing mostly just the full dumps to 200/100 GB LTO (Ultrium-1). 
> Since RAID-5 has less redundancy than RAID-1, I am more concerned about
> having at least some dumps on tape since a 2-disk failure would mean
> that all of the data on the RAID-5 would be gone.
> 

One of the concerns I have about disk-only based backup schemes is the
total loss of data.  If you encounter a 2-disk failure you lose not only
your most recent, but all your backups.  If a tape drive fails the data
can be read on another drive.  If a single tape goes bad, that is the
only set of backups lost.

Disk-based schemes seem to violate the amanda principle of never
appending to a tape.

All that negativity, yet I think I would setup a disk-based scheme for
ease and speed of recovery but as Jonathan does, I would do some backups
to tape also.  That is why I've been wondering about a RAIT scheme where
the backup is mirrored to disk and tape.


-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
 4455 Province Line Road        (609) 252-0159
 Princeton, NJ  08540-4322      (609) 683-7220 (fax)