Re: [SLUG] tape drive back-ups

From: Ian C. Blenke (icblenke@nks.net)
Date: Tue Dec 06 2005 - 17:07:07 EST


Mike Branda wrote:

>Hello all!
>
>Anybody have any experience backing up to tape with Linux?? Any drive
>suggestions? I've been looking at a Sony AIT-2 drive ( SDX-520C ) as I
>can get 50GB native / 130GB compressed per tape and I have a lot of data
>to back up (hundreds of gigabytes). Sony says the drive is Linux
>compatible and 2 companies offer Linux software for it...though they
>charge an arm and a leg. I was wondering how well the amanda suite
>works and any other suggestions as I have never worked with tapes. I
>assume that archives larger than one tape's capacity can span? Any
>advice and/or actual experience with tapes and/or this drive/media type
>would be appreciated.
>
>

It's arguably cheaper and easier anymore to use disk based backups.

When you can use a couple of less than $0.40/Gig IDE drives into a
mirror any use something like Dirvish (or rsync with --link-dest), much
of the reason for tapes goes away.

There are still reasons for tapes, but they're quickly dwindling. Per
gig, they are still cheaper. And a Semi full of tapes has an incredible
bandwidth (but horrible latency) when shipped offsite.

Tapes are notoriously slow. Tapes have a low finite read/write cycle
limit. Tape drives must be cleaned often, and backups must be verified
to ensure they were written properly. Like any magnetic medium, tapes
have an arguably "short" shelf life. As with any backups, backups to
tape should be tested periodically to ensure the backup software used is
making good backups that can be recovered from (you won't learn this
rule until you are bitten by it).

I would much rather use a farm of Linux servers with cheap IDE disks for
my backups spread between geographic locations (this is what we do at
NKS). Rsync is fast, easy to comprehend, and incredibly easy to restore
from. With rsync's --link-dest, hardlinks are made between backups to
files that are identical, saving disk space. The manpower of backups and
restores alone makes this fiscially the best thing to do.

If you are _still_ interested in tape backups, you're probably in a
datacenter backing up mainframes and other larger machines. In that
case, invest in a backup software suite like NetBackup (or if you're
using Windows boxes, possibly Backup Exec) and go buy yourself some
large SAN network that you'll spend too much money on, just to make
management happy. I hate Legato Networker with a passion. There are
other commercial packages for Linux like Arc backup, Arkeia, or BRU:
they generally all suck.

If you're an individual and _have_ a tape drive and a mess of tapes, and
want an opensource solution, then there's Amanda. I think I've seen one
other opensourced tape backup solution out there on par with Amanda
(though I've forgotten its name).

Anyway, that's my $0.02. I don't expect everyone to agree with me ;)

- Ian C. Blenke <ian@blenke.com> http://ian.blenke.com/

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