Jorge Peixoto de Morais Neto schrieb:
On Wed, Nov 26, 2008 at 12:26 PM, Florian Philipp
<[EMAIL PROTECTED]> wrote:
As for my photos, I can back all the collection to a single DVD (and
to a second one, since I keep hearing that DVD-Rs are unreliable), and
since I don't take new photos every week, this solution is fine.
A second DVD-R won't solve the problem because optical disks degrade over
time and the second one will degrade just as fast as the first. What you
need to do is to check the disks periodically (once a year is a good time
frame).
I know DVD-Rs degrade, but it is unlikely they would fail at the same
time, so copying twice does significantly alleviate the problem
(AFAIK)
I'm not so sure in this regard. If we were talking about HDDs you were
right: it is very unlikely for two of them to fail at the same time due
to mechanical defects. But we are talking about optical media. They fail
because of chemical reactions. That's why two disks, stored equally,
bought at the same time from the same trader, produced by the same
company, should degrade equally fast and therefore fail at about the
same time. And since you want to check them less than once a year, "at
about the same time" means within the same year.
Once a year isn't overkill? Isn't once every two years fine?
I'm not sure. I myself wouldn't trust normal CD/DVD-Rs for more than
three years and CD/DVD-RWs for more than one year (cheap RWs degrade
much faster than Rs).
Additionally, having such long intervals between checks makes it easier
to forget them completely. Can you remember whether you checked your
disks last year or the year before? I know I couldn't.
Sure. I am doing that since some time now. Unfortunately I didn't do
so for some old backups. But data DVD-Rs have a considerable amount of
correction code, and if the copy from DVD to hard disk proceeds
without a single error message, there is a quite good chance that the
files are good, right?
I would think so.
