Cost of DVD as data storage versus HDD (UK)

Daniel James wrote:

In article , GSV Three Minds in a
Can wrote:
Don't cross-post to so many groups (many people kill anything
crossposted to 3 places, on the assumption that if the OP doesn't know
which group it goes it, it won't be of much interest in any of them).

aside
.. and in doing so avoid a huge amount of junk and a few interesting
discussions.

I must say I'd find it "challenging" to dream up a post that could
legitimately be posted to more than about five groups, but I don't think
four is necessarily out of order.

The OP selected four groups for a posting which seems to me to be
reasonably on-topic for all of them ... except possibly uk.comp.homebuilt
(which is where I'm reading it, as it happens) where it is a common enough
subject fr discussion, if not strictly on-topic.
/aside

Back to the question .. cost per byte is not an interesting metric for
backups, unless you include the cost of making the backup and the cost
of securing it against whatever disaster you are backing up against.

.. and, perhaps more importantly, the value of the data.

People gaily make disk images of their whole system, but unless you can
produce =identical= hardware this is of no use at all if your original
system is stolen, ...

That's a good point, and one that's not made often enough.

If you have the original applications on CD, or you can buy
new copies from MS, there isn't much point in wasting time and money
making copies every day/week for the rest of your life.

Also true. One might think -- especially give the time it takes to install
some large applications -- that backing up once after an install would be
a time-saver, but in general when software is installed (on Windows, that
is) it sets a cartload of registry entries that aren't easily backed up in
isolation. Backing up the whole registry isn't useful if disaster forces a
change of hardware (which will mean the system-specific parts of the
registry will no longer apply). Reinstallation is really the only safe
choice.

That registry is a pain in the proverbial, sometimes.

For a large system a product such as Novell Zenworks can help deal with
this--it takes a snapshot of the system before and after an application is
installed, and after you clean up the excess baggage (something always
seems to change that has nothing to do with the installation) you can
quickly reinstall or install to other systems from the snapshot. It's also
very nice for figuring out what actually _did_ happen during the
installation when the installation hoses something.

In a perfect world, RAID1 or RAID5 for continuous up-time even if a disk
crashes (which they are increasingly prone to do), tape backups of
anything that can't be reproduced easily .. daily ones, or weekly, or
whatever turns out to be the best tradeoff between 'cost of prevention'
and 'cost of recovering what you hadn't prevented being lost'.

Good advice. Add to that that the daily/weekly backups (on whatever medium
they're made) should be test-restored so that you can be sure that they
*can* be restored, in the event of disaster (and that you've backed up
everything you need). Keep a spare device that can read the backups, in
case the original fails. Having a good tape backup regime is no good if,
when you need to restore some old data, you find that the tape drive is
knackered and that that type of drive is no longer available.

You can spend a fortune on backup and still not get it right -- and you
certainly can't get it all right without spending a fortune. How much you
do spend must depend on the value of the data.

Cheers,
Daniel.

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)