Repeating the caveat that I do not work for the Center for Electronic
Records & adding the usual disclaimer that I'm expressing my opinions,
not those of NARA., it's my understanding that use of magnetic tape by
the Center is a hardware obsolescence issue--not one of medium
longevity. While a disk may last fifty or more years, until standards are
developed there is no assurance that the disk can be read that far down
the road.
NARA's preservation program for the tapes calls for their recopying at
least every 10 years (and presumably their migration to a new medium if
a solid standard has developed in the interim). NARA will accept
transfers from agencies on CD-ROM now (providing the ASCII/EBCDIC
and other requirements are met), but they are copied back to tape for
storage and preservation....the CD-ROM is retained too, but the tape is
the primary preservation copy.
>>> Stewart Brand <> 02/20/98 10:37pm >>>
Fascinating. I see that NARA is relying on a storage medium standard,
which at present doesn't include optical disks. Here's a relevant
paragraph...
The National Archives maintains permanent electronic records for
subsequent use by the original agency, other agencies, other
organizations, researchers, and the general public. NARA
generally satisfies such demands by providing copies of files.
Because of the multitude of computers and the variety of software
available to present and future researchers, NARA requires
agencies to transfer permanent computer files in a hardware and
software independent format. Specifically, files must be written
on half-inch magnetic tape, in EBCDIC or ASCII, without internal
control characters, on 7 or 9 track open-reel magnetic tape,
recorded at 800, 1600, or 6250 bytes per inch, or on 18 track
3480-class tape cartridge, recorded at 37,871 bytes per inch, and
blocked no higher than 32,760 bytes.