[comp.sys.sequent] Exabytes on Sequent

arnold@jarthur.Claremont.EDU (Arnold de Leon) (02/15/90)

Sequent is now offering an 8mm solution for the Symmetry.  From what I've
heard it does not use the SCSI bus on the SCED board but instead uses a
controller on the Multibus.

Does anyone have experience with it?  Are they using a Pertec to SCSI
board?  If so can it share the same Multibus controller as a 1/2 inch
tape?  Any information is appreciated.

-- 

Arnold de Leon                       arnold@jarthur.claremont.edu
Computer Science Dept., HMC          uunet!jarthur!arnold
Claremont, CA 91711                  arnold@hmcvax.bitnet

keith@sequoia.UUCP (Keith Pyle) (02/17/90)

We have just ordered an Exabyte for our S81 from Sequent.  This is considered
a custom item and comes from their custom systems group.  The controller is
the same as used for a 1/2" tape for the MEU (Model TPU-0000-20).  Since we
don't have it and Sequent won't set a date for delivery for it or the other
items we've ordered, I can't give you much more information now.  When we
get it in and have some experience, I'll post our impressions here.

On the topic of these other items we ordered, anyone have a 24 MB ECC memory
expansion card available short term and reasonably priced?
-- 
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Keith Pyle                                UUCP: ...!cs.utexas.edu!execu!keith
Manager, Data Processing Services Dept.   Internet: keith@execu.com
Execucom Systems Corp.                              execu!keith@cs.utexas.edu
108 Wild Basin Road                            keith%execu.uucp@cs.utexas.edu
Austin, Texas 78746                       Ma Bell: 512-327-7070
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jr3w+@andrew.cmu.edu (John Davis Raborn) (02/20/90)

We are using a MegaTape 8mm tape (shipped by Sequent) unit on our
Symmetry 27. I love the damn thing. It's fast (relative to 9 track). 

We have it's controller on the multibus along with the 9 track
controller. I have plans to eventually move my monthly dumps to 8mm so
the two devices would be working together. I'm assuming the controllers
will be "smart" enough to work together, which of course is a danagerous
assumption due to speed, block size, etc. It has been suggested by
Sequent that there shouldn't be a problem here. We'll see.

We run automated backups at 3:00 am every weekday. The tapes hold about
2.04 gig, which is fine for us, so far. Everything has been a real
plaesure. Some notes:
1. DUMP can't handle the helical scanning, so you get HDUMP with the
package. It's just a modified dump, basically, the same parameters.
2. RESTORE works fine.
3. We are working with big density, ie, 3.95 bpi on the drive.
4. The only "problem "I've had  has been with MT commands. I get thrown
off line alot. The manuals talk about it, but i tried it any way. REWIND
and FSF are ok, but BSF causes the problems. However the 8mm is fast
enough that it isn't that much of a pain to REWIND and FSF instead of
BSF. REWOFFL is ok too.

Please realize that I use the term FAST with caution. At first my
expectations were let down, but the more I use the drive , the more I
love it. The drive does a lot of work. For example, it often retensions
itself depending on the command, so that takes a few seconds (a
minute??). Also, if EJECT is hit, I believe it retensions itself again. 

Davis Raborn
Carnegie Mellon University
Administrative Systems
UCC 167
Pittsburgh, PA 15213
work: 412 268 8554

jr3w+@andrew.cmu.edu (John Davis Raborn) (02/21/90)

I made a misprint:

>3. We are working with big density, ie, 3.95 bpi on the drive.

Instead of 3.95 bpi it's 3.95 Mbpi!!!!


Davis Raborn