A file archive is a repository in which data must be kept safely and indefinitely.
For example, seismic data and earth observation data collected by satellites
are generally kept in a file archive. The architecture of an archive system
can be similar to the file server system described above. However, the
emphasis in a file archive is on the low cost of storage and high reliability.
The media used in a file archive must be stable over time, economical
and reasonably fast. The bulk of the data in a file archive is stored
on magnetic tape. (In studies undertaken for major tape hardware vendors,
the characteristics of tape usage have shown consistent similarities across
library size and industry barriers. For example, the average amount of
data stored on a tape tends to be bimodal. The average tape is about 25%
full. If one were to examine each tape in the library, however, one would
find approximately 75% of the tapes were full to less than 5% of their
capacity and the rest were 100% full).