tape drive info wanted.

[Richard Foulk]

>If you want a high capacity and high speed backup drive both 4 & 8mm will do.  
>
>If you want to be able to share data via the tapes, you will have to get
>a QIC drive because it is the prevalent format and because most people can't
>afford the extra cost of the high capacity tapes.

Change that to say "most can't afford the high capacity tape DRIVES".

The 8mm tapes themselves are much less expensive than QIC tapes.  You
can buy them at the drug stores around here for $7.  In case-quantities
they're even cheaper.

I think this puts the cost-per-megabyte with 8mm tapes at about 1/30th
that of QIC tapes.

Don't buy certified data tapes -- they're a lot more money for the same
item.  Regular Sony video tapes perform just as well.  El-cheapo tapes
also work fine, though the recoverable errors count becomes non-zero.
(Error correction capabilities on the Exabyte drives are very
impressive and seldom used -- at least with Sony tapes.)

If you expect to use a fair number of tapes over the next year or so the
Exabyte drive could ultimately save you money.

>>- Exabyte is the sole manufacturer of 8mm tape drives. They have
>>  higher bandwidth and capacity than 4mm tapes. They may do a better
>>  job of read/write error handling.
>
>I find this hard to believe, especially when you pick up a copy of a 
>unix rag and find advertisements from companies like media cybernetics
>who have thier own 8mm product.

All the 8mm vendors buy from Exabyte, a subsidiary (or something like that)
of Sony.

Note that 4mm drives are much newer, slower, hold half as much, use more
expensive tapes, and (from my reading of the specs and technique) don't
use nearly as good an error recovery approach.

The 4mm guys are now boasting numbers that compete better with Exabytes
in speed and capacity -- they gain this new level of performance by
adding compression to the interface :-(.  This means the capacity
varies according to your data, and amounts to a net loss if the files
you're writing are already compressed.  (They often mention the
compression in small print, if at all.)

Check the sun-spots mailing list archives of a year or two ago for a lot
more insight into the development and ins and outs of the Exabyte drive.

BTW: as far as data-sharing goes, I think UUNET makes their archives
available via 8mm tape.


-- 
Richard Foulk		richard at pegasus.com