[Gllug] Viable back-up solutions for gigabytes?

Russell Howe rhowe at wiss.co.uk
Sun Sep 5 09:12:59 UTC 2004


On Sun, Sep 05, 2004 at 09:44:28AM +0100, Martin A. Brooks wrote:
> I'd guess DVD would most likely be fine for you, though I would take the 
> added precaution of storing the backups in a lightproof box.

I'd also work to the assumption that a disc isn't going to last more
than 2-3 years, and duplicate any discs you keep longer than this.

The media and drive costs are so low that this is a perfectly reasonable
thing to do. If you make 2 or 3 copies of your data (DVDs, unlike tapes,
can of course get scratched, bent, snapped, etc) and keep them in two
locations (one near the machine for emergencies and one further afield
for disaster situations), you'll be much better prepared in the event of
data loss, for quite a small expenditure.

Tape systems are generally good, reliable, durable, have quite long data
retention times (although I think MO is often touted as having the
best?) and the more modern drives are fairly quick. There's also been a
lot of investment in things such as tape libraries and robots to manage
huge archives. Tape systems tend to be expensive though, and therefore
tend to be used by those who would be in for a severe financial loss
should their data go the way of the fairies.

For personal use, DVD backup with a media replacement strategy is fine
IMHO.

Oh, and you can post DVDs cheaply - try posting a DLT tape without
paying extra postage :)

As if that weren't enough, most DVD writers these days also support
writing to CDs, so if you have 700M or less to backup, then you can
always fall back on CDR media which can be bought in bulk for around
15-20p each.

Some people make backups to hard drives, but these devices weren't
really built as backup devices and the whole reason we have RAID is
because people *expect* HDs to fail.

Having a copy of your data on a spare HD is always handy though - large
ones can be bought fairly cheaply, and they're fast. Good for when you
accidentally rm -rf /tmp/junk /* :)

I think with the software RAID driver, md, you can also designate a
drive (or set of drives) as spares, so if an md array suffers a failed
drive, md can bring a spare drive online and start rebuilding the array.
Presumably the thinking here is that if the drive isn't powered up, it's
not going to wear like the running drives. Doesn't help you if you have
a power glitch which fries all the devices attached to the machine,
though.

Obviously the best backup solution would be to have all your data on
something like RAID6, with 2 or 3 spare drives in the case, a hot backup
on a removable HD, a local copy on a large capacity DLT tape and another
copy in secure storage somewhere offsite, preferably in another city.
Something tells me you wouldn't feel the expense is worth it, however :)

You could always get the photos printed and post them to all your
relatives - distributed off-site backup :)

Apologies for the ramblingness of the email - it's too early to be
Sunday

-- 
Russell Howe       | Why be just another cog in the machine,
rhowe at siksai.co.uk | when you can be the spanner in the works?
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