On Mon, Jan 07, 2008 at 01:22:53PM +0100, knitti wrote:
quoted text
> Backup (and/or archiving) is not fire-and-forget. You have to know how
> long you want to store this data to choose the right technology and
> media. And you have to have a process to verify that your data is good
> after this time. If you want backups for five years, and your life/business
> won't come to an end should you lose some data in spite having backed
> up, use DVDs or HDDs, verify after backup and just store the media.
> For more than five years and more-or-less critical data, use tape and
> verify every x time. If you approach ten years and up, you have to
> know how you get hardware to read the tapes...
> 
> At least the LTO spec states that drives of the *current* generation
> _have to_ read and write also tapes one generation older and
> read tapes which are two generations older. So if you have LTO-2
> tapes around, you will be able to read them with LTO-4 drives (which
> should be checked, but does actually work in this case).
> 
> Some companies and universities with huge archives spend
> large sums just to copy their archived data to the newest technology
> every couple of years.

So lets take the case of a home user with lots of data, perhaps home
movies.  Sure, those movies can be burned to DVD for watching, but then
they're suceptible to scratches.  You could make a second DVD to put on
the shelf somewhere but kids grow up and you may want to have say 20
years of home movies around for a lot longer.  Lets say the movie
archive size increases by 20 GB (compressed) per year.  At that rate,
tape really starts to look viable. 

The home user probably wouldn't wear out a tape drive (tape pass count
or hours of operation -wise) but how well do they age?  Lets say you buy
a second-hand one-generation-old tape drive and use it to store DVD
images of home movies (plus long-term backup of general data).  Other
than finding that you start archiving more and more (well beyond the 20
GB per year), would there be any reason to worry about having to change
to newer technology in a few years?

What about slightly older technology, perhaps a DLT-IV 40/80 GB drive
(e.g. HP Surestore DLT-40/70/80)?  Those are quite inexpensive used now,
what would be wrong with getting one of those for archival.  Heck, get
two, one to use, the other to store in the archive?

Doug.