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Re: off-site backup

On Fri, Oct 13, 2006 at 10:51:56PM -0400, dtutty@porchlight.ca wrote:
> I'm reviewing/planning for new offsite backup media and am wondering
> what people are using now.  Previous discussions I found on
> lists.debian.org are a few years old.
> I've been happy using 100 MB Zip disks; I can store everything except
> CD-iso images on one or two and put it in the bank's safety-deposit box.
> However, it has meant that I've had to burn to CD collections of
> documents that I would preferr to keep online.  Then I end up with a
> separate directory which is NOT backed-up to keep them online for
> viewing.  My drives are over 10 years old and the media is close to it.
> Time to migrate.
> I can use small CD-R but they only hold 175 MB.  Full-size CDs don't fit
> in the bank's box.
> My new computer (Athlon-based) will have two 80 GB Seagate Barracuda
> SATA drives in a raid1 configuration to handle drive failure.  I'm
> looking for removable media to handle both data-failure and platform
> failure (or local disaster).  
> At this point, I'm specifying a backup-set size of 10 GB although if the
> media I choose is cheap enough, I would like to backup CD ISO images to
> protect that data from CD scratches or other failure.
> Physical size:  A Zip jewel case is 4-1/8" and fits the bank, a CD jewel
> case is 4-3/4" and doesn't.  
> Minimum number of backup sets, 3: one in the drive, one on the shelf,
> and one in the bank.  I'm looking at media at this point, not procedure.
> I don't have a requirement to see what a file looked like months ago.
> Also, this is in addition to online backups (in /var/local/backup).
> I want physical robustness.  CDs are prone to scratch and I understand
> that for all they're 'burned' with a laser there is some dye involved in
> the process and they can fade in bright light or heat.  Able to
> withstand a 1 m drop would be good, e.g. after its removed from its case
> and before it gets into the drive.  
> 10 year shelf life seems to be a common criteria for backup/archive
> media.
> I think that tape is overkill for only three sets of media; the drive
> and SCSI card are too expensive.  
> There are Iomega removeables called Rev.  I don't know what real-world
> reliability and longevety is like.
> Quantum has a removable thing called GoVault that is basically a
> ruggedized cartridge with a laptop-drive inside.  I don't know what
> real-world reliability and logevety is like.
> There are generic ruggedized drive caddies but I understand they're not
> hot-swappable and I don't want to have to shutdown to change media.
> At the small-end there's USB sticks but I don't know what the shelf-life
> really is (other than Kingston's 5 year warranty).  Size-wise, this
> would work as a floppy-replacement for the must-always-be-able-to-read
> stuff (i.e. immediatly readable from any computer, linux or not, msdos
> fs with plain-text, e.g. critical email).
> Interface options I have now are eSATA, USB, Firewire.  Anything else
> needs a card too; add it to the cost of the drive.
> Given the choice, I would prefer external instead of internal.  In case
> of a disaster-in-progress (e.g. house fire), can grab the drive and go;
> or if something catestrophic happens to the computer, the drive may
> survive.
> All else being equal, I would prefer cheaper to expensive on a per-set
> basis.  E.g. tape is probably chepest on a per GB basis (or is that per
> TB) while USB stick is most expensive, but for 2 GB, USB is probably
> cheapest per set.
> What is you wisdom on this in-between area (more than a CD, less than
> LTO or DLT)?

Is backing up to a USB connected hard disk not rugged enough?  The ones
using laptop drives should be fairly durable, and rather small in size
too.  The drive caddies that go inside the case don't make much sense
for this unless it was a hotplug cage for sata or something.
Unfortunately linux does not yet support sata hotswap, although most
sata controllers can support it.  eSATA would even be handy for that if
linux had support for that.  One way to backup in such a case would be
to connect a drive the same size as the raid1 you have, and add the
backup drive as a 3rd mirror to the raid, let it rebuild (remember to
reduce the max rebuild speed enough to not make the machine unresponsive
for normal use), and when done, drop the usb/other external drive from
the raid again, and you have a perfect mirror as of that moment.  It
could even be made bootable if you install the boot loader on it too.
Great backup and disaster recovery since you have a copy of your drive.

Len Sorensen

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