Philip
As already noted I believe lifespan of computer media is directly
affected by storage conditions. The most critical environmental factors
are temperature and humidity.
Stored in a stable environment at 10 degrees C and 25 RH a recent survey
suggested the following lifespans
D3 magnetic tape 50 years
D3 magnetic tape cartridge 75 years
CD/DVD 75 years
DAT tape 30 years
At 28 degrees C and 60 RH these become
D3 magnetic tape 1 year
D3 magnetic tape cartridge 1 year
CD/DVD 2 years
DAT tape 3 months
The survey assumes minimal access to the media (ie archival copies) and
that conditions are stable, free from contaminants, u-v light and strong
magnetic fields (see
http://www.jisc.ac.uk:8080/dner/preservation/workbook/).
Clearly in optimal conditions most media will outlive the hardware
needed to use it unless stategies of hardware preservation or emulation
are followed. Both of these stategies have problems; maintenance and
finding parts in the former and designing emulators as hardware becomes
more and more remote (advanced) from the original in the latter case.
The alternative is to regularly refresh data and migrate it to new media
as necessary. Migration is see as the only viable long term solution by
many organisations including the ADS.
Various sources suggest the lifespan of a floppy disk is as little as
1-4 years! Hard drives many last many years but crashes can happen at
any time and may lead to data loss. It is at such times that a well
planned back up strategy comes into play (see Fernie, K. & Gilman, P
(eds). 2000. Informing the Future of the Past: Guidelines for SMRs,
English Heritage).
Other sites of interest include http://www.emafoundation.org/docs8.htm
and links therein and an otherview of 'new media' at
http://www.pro.gov.uk/preservation/guides/
Tony
Philip A Greatorex wrote:
>
> Does anyone know of any study/information relating to the suitability of
> computer media for long-term data storage?
> In particular the projected lifespan of different media types (Hard-disk,
> floppy, tape, CD etc.)
> Phil Greatorex, Gloucester Archaeology Unit
--
______________________________________________________
Tony Austin http://ads.ahds.ac.uk/project/staff.html
Computing Officer
Archaeology Data Service
The King's Manor
York
YO1 7EP
UK
phone +44 (0)1904-433975
fax +44(0)1904-433939
http://ads.ahds.ac.uk/catalogue/
______________________________________________________
|