Re: [SLUG] tape drive back-ups

From: Paul M Foster (paulf@quillandmouse.com)
Date: Wed Dec 07 2005 - 18:40:25 EST


On Wed, Dec 07, 2005 at 10:46:23AM -0500, Mike Branda wrote:

> On Wed, 2005-12-07 at 01:11 -0500, Kwan Lowe wrote:
> > > I have to agree with Ian. I used to back up our office machines to tape.
> > > This was using an IDE tape drive that accepted up to 3G Travan tapes.
> > > Slow as hell to back up, and it was hit or miss whether the backups
> > > would actually work or not. These suckers would spin one way for a
> > > while, spin another for a while, and generally take an order of
> > > magnitude or more longer to back up to than disk.
> >
> > I prefer to run two-stage backups on my customer machines... Tar several
> machines to
> > a shared disk then steam the tars to tape. This decreases the backup
> window on the
> > individual machines and generally speeds up the tape write.
> >
> > >
> > > These days, I selectively back up certain mission-critical data to a
> > > spare hard drive on another machine, and periodically make CD backups of
> > > that. All driven by cron jobs, for which I get a message every day,
> > > telling me how it all went.
> >
> > And that is exactly what I do for my personal systems.
> >
> > BACKUP_LIST="/etc /var/named/ /var/www/ /var/spool/mail /home/draken/mail
> "
> > BACKUP_PATH="/export/backup/host001/"
> >
> > ssh root@host001 "cd /; tar -cf - ${BACKUP_LIST} "|(cd ${BACKUP_PATH};
> tar -xf - )
> >
> > Then I use K3B to write the backup dirs to DVD.
> >
>
> Paul and Kwan,
>
> This would be great if I wasn't talking about Gigabytes of data. In my
> first post I wrote that I was thinking about using the AIT-2 drive
> ( SDX-520C ) as I can get 50GB native / 130GB compressed per tape. And
> someone recently enlightened me to the fact that "AIT stores the tape
> catalog on some form of memory chip (most likely flash) inside the
> cartridge which in turn reduces the number of times it has to rewind and
> advance the tape." My current backup is a nightly rsync of three 1.2TB
> SCSI Raid 5 Array servers to a 4.3TB 24 disk Raid 5 backup server in
> house.

Suggestion #1: Get carrying straps those puppies for offsite storage.
;-}

Suggestion #2: Open about a hundred Google Mail accounts, and email the
backups to them. ;-}

> There's some good redundancy and fail-over there until the
> building burns down. In my mind I was thinking that tapes have less
> moving parts and less to go wrong than platter media.

Dunno about that. Tape drives are more complex than disk drives, and
more subject to dirt and grime. Tape cartridges are pretty complex, too.
If you're using reel tapes (I don't know what the AIT is), that's a
different matter. Of course, if you're actually talking about backing up
terabytes of data, I dunno. That's a lot of tapes or disks, no matter
how you cut it.

FWIW, at my old employer, they used to do a nightly backup on NT using
Backup Exec. I don't know how many times they had bad backups. On top of
which, the program would freeze the machine a lot. Things have probably
changed, but I'd be leery of trusting a Windows based solution. The dump
command was made for exactly this purpose, and it ought to be on any
Linux box you have. Of course, from what I've heard, dump isn't all that
great either. The problem with dump and tar is that if something happens
in the middle of the volume, the rest of it's gone. Not so if you back
up individual files to disk/tape (using bzip or gzip).

Suggestion #3: Crack open a Linux Journal and a Linux Magazine and see
if there aren't ads for something along these lines. Linux Journal is
the geekier of the two, and I usually see a lot of pretty geeky stuff in
ads there. (No smiley on this one!)

> Also that the AIT
> Drive was more advanced and had a larger storage capacity than other
> tapes. The Data would be compressed and I guess I could fit it on a
> portable drive or 2. I was just hoping to try to have a different media
> type and one that was smaller and easier to transport off site.
>

Suggestion #4: Use the new Black Hole compression algorithm. You can
back up everything you have onto a few atoms. Of course, you have to
travel to the next universe on the left to do a restore, but really, how
often will you have to restore? ;-}

Paul
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