Re: Long term archiving - which brand of CDROM do you recommend?
Hi,
> can anybody please give me some recommendations for long term archiving of
> data.
> Which brands are known to be usable for this?
Brands are not a reliable guideline, i fear. You can read different
manufacturer ids from media of the same brand, just bought a year
apart (or just a shop apart).
Even Verbatim has gone promiscuous meanwhile.
If you successfully checkread the archived media after writing,
then you have good chances for a long life of the archive.
You should of course re-check during that lifetime.
I would store at least two copies at different places and hope
that the second copy is still ok when the first one fails its
yearly test (or vice versa).
The more copies, the more hope.
My oldest (outdated) CD-RW backup is from 2003 and still passes
the yearly random sample test. (One out of 60 CDs is checkread.)
It will be convenient and more fool-proof if you store checksums
on the same medium which they shall guard.
Actually the optical media all have own checksums and error correction
which are used internally by the drive. I had two cases, though, were
DVD+RW media returned false data without error indication.
So an own MD5 or SHA-1 helps to make clear that the data are still
as they should be.
One may discuss whether the lower density of CD or the more
sophisticated checksums of DVD and BD are to prefer.
I would make the proposed copies on media of different manufacturer
and/or media type (e.g. DVD-R versus DVD+R).
Said this, my youngest BD burner bears a logo "M (swirl) DISC",
which means "Millenial Disc". This is DVD+R or BD-R with mineral dye.
http://en.wikipedia.org/wiki/M-DISC
The web shows positive and negative opinions.
One thing is certain: They are more expensive than other media
of the same capacity.
There are archive formats like RAR, which are prepared for the
loss of chunks of archive data.
http://en.wikipedia.org/wiki/RAR
Optical media are supposed to fail partially first. So there is hope
that in the beginning of deterioration, enough redundant intermixed
archive parts stay readable.
Have a nice day :)
Thomas
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