Re: Backup devices

[Maurice Hilarius <maurice harddata com>]

With regards to your message at 10:54 AM 1/4/00 -0500, Uncle George. Where 
you stated:
> Tell me, how long do the data on the tapes last ? 1 year, 5, 10, 25 years ?  |
> are these drives just short term backup devices. ?
> signed
>     afraid to look at my 8" floppies !
General "rule of thumb":
Streaming tapes, low density, like DC6000: 5 yrs. "shelf life of data"
Of course every time you re-write them they are refreshed, so now the only 
question is how long for the plastic base to get brittle and fail, or the 
oxide coating to separate from the backing.
For helical scan, like 4mm DAT, and 8mm Exabyte, it is usually 2 to 3 yr. 
shelf life. These units also run the tape over a more complex and 
convoluted path on rollers, so probably will not last as long.
Finally the newer digital tape formats like DLT, AIT, and Ecrix are a more 
advanced technology, with more data redundancy, and their manufacturers 
have claimed longer shelf life ( as much as 30 yrs.) Obviously none of them 
are actually this old, so the claims are based on "accelerated testing 
procedures".

Newer types like DLT actually load the whole tape onto an internal spool 
every time they load, so tensioning is more precisely managed, and I 
suspect this will contribute to a longer duty life as well. For DLT I have 
seen claims of 50,000 load/unload cycles..



Best regards,

Maurice W. Hilarius       Telephone: 01-780-456-9771
Hard Data Ltd.            FAX:       01-780-456-9772
11060 - 166 Avenue        mailto:maurice@harddata.com
Edmonton, AB, Canada      http://www.harddata.com/
   T5X 1Y3