Optical Disk add-on

[Mark Bradley]

In article <8908181458.AA10756 at aero4.larc.nasa.gov>, blbates at AERO4.LARC.NASA.GOV ("Brent L. Bates AAD/TAB MS294 x42854") writes:
> 
>    I don't know about the interfacing problems, but I thought the
> last time I looked at the price for MO and WORM drives they looked
> very competive as far as Mb/$, when compared against a regular
> magnetic disk (especially if the magnetic disk is purchased from
> SGI).  Especially since you can use multiple disks in the
> MO and WORM drives.  Also, they ARE random access.  It sounds
> rather ridiculous to me to call a DAT a random access device.
>    WORM drives look very promising if you need fast access to large
> permanent archives.
> --

It is not ridiculous at all.  They were designed to be random access
by virtue of directory structures resident on tape so that the drive
will 'know' where to go for the data.

There are 2 different approaches to getting this capability.  One is
the Sony/HP DDS format and the other is the Hitachi/Maxell format.
Both have their benefits, although the Hitachi requires a formatting
of the tape media, much like the formatting of disk drive media.

And talk about cost/MB.  I believe that list price from some distributors
will be <$5K for 1.2 GB.  

					markb


--
Mark Bradley				"Faster, faster, until the thrill of
IO Subsystems				 speed overcomes the fear of death."
Silicon Graphics Computer Systems
Mountain View, CA			     ---Hunter S. Thompson