Re: off-site backup
On Mon, Oct 16, 2006 at 09:33:21AM -0400, Lennart Sorensen wrote:
> On Fri, Oct 13, 2006 at 10:51:56PM -0400, firstname.lastname@example.org 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.
> > 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 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.
> 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.
The encased USB laptop drive option in where I'm leaning after last
night's research. Looking at how fragile a DLT cartridge is (basically
drop it and its broke/unreliable even if it looks ok) compared to
several drive enclosures that say they protect the drive at 1 m onto
concrete, it makes the point.
I was especially interested to find that the cost difference between a
DLT cartridge and a comparible disk drive is getting smaller all the
time. One wonders how long tape will be cost-effective even for
I had wondered about the shelf-life of hard drives compared to DLT but
since so many big names are making disk-based virtual tape drives, it
suggests that they are comparable.
Not that I'm puting data on a media (tape, drive, whatever) and leaving
it for 10 years. I'm keeping the data current by cycling media through
attached-shelf-bank monthly. Critical data that always needs to be
up-to-date I'll probably use USB sticks for. Those files are plain-text
so that they can be read from any computer that can mount the USB stick.
It seems that USB sticks/flash-drives are far more rugged than anything
other than paper. What have you found?
At this point, I hadn't considered using the raid1 system to mirror
everything onto the drive but that does make a lot of sense at least for
the base system to keep a working snapshot off-site.
Since my MB has an eSATA port on the back, I would like to use it for
the backup, although I also have USB and Firewire. What is it that is
keeping eSATA from being hot-swapable? Is there an ETA on this?
Len, have you written a book or anything?
Thanks for your wisdom,