🚀 go-pugleaf

In article <2400029@kailand>, pwolfe@kailand.KAI.COM writes:
> 
> I've recently received information about the EXABYTE EXB-8200 8mm cartridge
> tape subsystem, with which one may store up to 2 Gigabytes (2,000 Megabytes)
> on a single tape cartridge.  Sounds very attractive for running unattended
> overnight backups.
>
> 	- can anybody relate any experiance with this particular device?
> 	- is Sequent's SCSI (ANSI X3.T9.2) capable of supporting this drive?
> 	- do you have any info on connecting SCSI peripherals to Sequents?

I'm not certain how useful this will be, but the folks at Perfect Byte
tested the EXABYTE on our B8K, connecting it in place of the usual cartridge
drive.  The DYNIX driver for the cartridge tape worked reasonably well,
although the EXABYTE supports some operations not included in the driver.
We were successful in reading and writing with no significant changes
whatever.

-- 
Stan Wileman			uucp: uunet!btni!unocss!cs002
Math/Comp. Sci. Dept.		Inet: cs002@unocss.unl.edu
U. of Nebraska at Omaha		Bitnet: cs002@unoma1.bitnet

In article <2400029@kailand> pwolfe@kailand.KAI.COM writes:
>Actually, I was wondering if any gurus out there could tell me:
>	- how difficult is device driver software to work on?
>	- can anybody relate any experiance with this particular device?
>	- is Sequent's SCSI (ANSI X3.T9.2) capable of supporting this drive?
>	- do you have any info on connecting SCSI peripherals to Sequents?

We have an Exabyte on order.  We're going to experiment with it
on our Symmetry 81.  If there's people out there that are interested
in the results, I can post our experiences.

If memory serves, Sequent is evaluating the Exabyte even as I write.
(Source: The last SURF meeting.)  As I recall, the issue was not the
interface between the Exabyte and the Symmetry, but that the Exabyte
had reliability problems.  I guess we'll find out.  We're presently
buying over $9000 worth of 9 track tapes a year for daily incrementals,
and *that* has *got* to *stop*!

According to the Exabyte rep, the drive looks like an Archive streamer
(with a very looooong tape) to the SCSI controller.  He said that at
least on the Sun, the same driver works for the Archive and th Exabyte.
We are betting that the Archive driver on the Symmetry will also talk
to the Exabyte.

				Ron
-- 

      Ronald O. Christian (Fujitsu America Inc., San Jose, Calif.)
      {amdahl, pyramid, sun, unisoft, uunet}!fai!ronc -or- ronc@fai.com

In article <1180@fai.UUCP> ronc@fai.fai.com (Ronald O. Christian) writes:
...
>
>If memory serves, Sequent is evaluating the Exabyte even as I write.
>(Source: The last SURF meeting.)  As I recall, the issue was not the
>interface between the Exabyte and the Symmetry, but that the Exabyte
>had reliability problems.  I guess we'll find out.  We're presently
...
At a recent SURF meeting in Newport Beach, I asked a Sequent Tech Support
guy about the Exabyte.  He said that Sequent's SCSI was so finely tuned
that he guaranteed the Exabyte wouldn't work.  I'd be happy to hear that
Sequent had solved that problem and could connect an Exabyte (or any
similar drive) to the SCSI.


Neal Thompson
neal@hacgate.scg.hac.com

In the UK, Compass sell the Exabyte tape streamer device
with a Pertec interface.
This is good news because the Balance tape device driver has a
Pertec interface, and so we can use the DYNIX we've got without
modification.

The cost of the Exabyte unit is #4944, the cost of the tape
controller is #1683. Maintenance about #50 per month. Tapes are
standard 8mm video tapes (prices as at July 1988).

We have had this device on order for a long time now (months),
but we are getting a curious extra: it will have a switch on
the front which connects the drive to an alternative controller
that in our case will be fitted inside our VAX 11/750 so that
that can write streamer tapes as well.
-- 

William Roberts         ARPA: liam@cs.qmc.ac.uk  (gw: cs.ucl.edu)
Queen Mary College      UUCP: liam@qmc-cs.UUCP
LONDON, UK              Tel:  01-975 5250

Followups directed to comp.periphs.

[Doesn't anyone at Sequent read their own newsgroup? Sheesh.]

In article <1180@fai.UUCP> ronc@fai.fai.com (Ronald O. Christian) writes:
>As I recall, the issue was not the interface between the Exabyte and the
>Symmetry, but that the Exabyte had reliability problems.

When I first saw the 8mm drives, I thought they could be a real godsend for
machines with disk farms. (2 GB on a tape smaller than an audio cassette!) And
for certain environments, they may well be. But the problems I observed were:

- The 8mm drives are slow. You save a lot of storage space compared to 9-track
  reels (something like 13 9-track tapes to 1 8mm cartridge), but backups take
  about twice as long. Figure about two and a half hours per tape. Of course,
  you'll have to change tapes 13 times less often....

- The actual transport mechanism is made by Sony, no matter whose name is on
  the box. These are consumer quality, designed for use in Camcorders, with a
  low duty cycle. (Say, a few hours a week.) Run continuously, ours died in
  less than six weeks. Less use would give longer life, of course.

- Media integrity is *highly* dubious. These tapes are again consumer quality,
  where all you have to do is get enough bits right to create a viewable TV
  picture. Data storage is a whole 'nother story. I would not expect an 8mm
  cartridge to hold usable data for more than a year or so. So you'll still
  need something like 9-track for monthly dumps and such.

- Sony has been privately telling potential customers to wait for computer-
  grade DAT drives. These have about half the storage of 8mm, run at about
  the same speed. Supposedly both the media and the drives are more reliable
  than 8mm.

One oddity, too. Pyramid and Sequent aren't selling to PC users; anyone who is
spending >> $100K on a computer is buying something to set in the data center.
It has to look impressive on the balance sheet. And there's this image problem
of telling the Data Center staff that they should be buying blank backup tapes
at K-Mart or Tower Records.... (Sony actually will sell you "data quality"
tapes at about four times the price you can buy them from K-Mart. Same thing,
as far as anyone can tell.)

The natural technology for production use would seem to be the good ol' 1/4"
cartridge. The state-of-the-art here seems to be QIC-150 drives from Cipher,
Tandberg, and others: 150MB on a 600 foot tape. This is essentially the same
amount of storage as a 6250bpi 9-track reel, with comparable recording times.
The interface is usually SCSI or Cipher.

This is a long ways away from 2GB per tape. Given the relatively controlled
nature of the transport in a 1/4" cartridge, you would think that more modern
encoding techniques* would yield incredible amounts of storage, perhaps 10GB,
with high speeds and high reliability. But for some reason no one is willing
to pursue this; they're mucking about with toy tape drives instead.

* If you want to get rich, figure out a cheap way to do helical scan on a 1/4"
cartridge tape.

<csg>