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- From: CZIWKGA@VMSFE.ULCC.AC.UK ("Kevin Ashley, Systems Development, ULCC")
- Newsgroups: comp.os.vms
- Subject: Summary: Using Micro Technology Exabyte 8500 in low density
- Message-ID: <9207281641.AA07842@ucbvax.Berkeley.EDU>
- Date: 28 Jul 92 14:46:00 GMT
- Sender: daemon@ucbvax.BERKELEY.EDU
- Distribution: world
- Organization: The Internet
- Lines: 59
-
- Thanks to all who responded to my question regarding the use of Exabyte
- 8500 drives supplied by Micro Technology to write low-density (2.2GB)
- tapes. Although no-one was able to solve my problem, your responses
- convinced me that I have an issue to raise with Micro Technology here
- in the UK.
-
- To remind you of my situation, the drive is connected via a QBUS interface
- to a Microvax 3600. The interface must, I presume, perform some intelligent
- conversion, making the drive appear to be a TU81 to the QBUS, but speaking
- SCSI commands to the Exabyte. Some peoples's suggestions were, unfortunately,
- specific to different controller suppliers or to different environments,
- such as those where the Exabyte is connected to a SCSI bus on a VAXstation.
-
- Most everyone suggested using INIT/DENSITY=1600 for low density and
- INIT/DENSITY=6250 for high. This had occurred to be before I sent my message,
- and I probably should have said so. I had tried it, and it doesn't work.
- SHOW DEVICE always reports that the drive is operating at 1600 bpi, but
- in fact it is always writing high density tapes. However, it is clear
- that this is how it is meant to behave. One responder commented that the
- firmware needed to be at the right rev level for this to work. This could
- be our problem.
-
- Others suggested initializing a tape in the low density drive we have, and
- then using it in the high density drive, without rewriting the label - that
- is, specifying /NOREWIND to BACKUP, since that is my main use of it. I had
- tried this as well. It also didn't work. One responder said that, for
- this to work, one had to prevent the tape being rewound after the reading
- of the label. BACKUP always seems to rewind the tape to perform label
- verification, and although the drive indicates that it is in low density mode
- when reading the label, it then switches to high density mode when writing
- begins. (I assume this from looking at the Tape Remaining indicator, which
- reads in Mbytes remaining.) It may be that BACKUP will perform differently
- if there is an empty saveset first on the tape, rather than just labels.
- I will try this as well.
-
- However, it seems clear that we really need to get the controller up to rev,
- since using INIT/DENSITY works for so many other people. Thanks to all of
- those who took the time and effort to respond to my question, specifically:
-
- russell@org.erim (John Russell)
- Richard Seymour <seymour@edu.washington.u>
- COLOMBO@gov.fnal.fndcd (Rick 'VMS lives 4ever' Colombo)
- fox@edu.msu.nscl.rudolf (Ron Fox)
- daveg@com.clearpoint.prowler (Dave Goldblatt)
- Jim Ross <ROSSJI@mil.af.js-jtf>
- Roy Omond <Roy.Omond@DE.EMBL-Heidelberg>
- John Macallaster <macallstr@vax.ox.ac.uk>
-
- and others whose addresses I have lost - apologies.
- ------------------------------------------------------------------------------
- Kevin Ashley K.Ashley@Ulcc.ac.uk
- Systems Development Group Manager Telephone: +44 71 405 8400
- University of London Computer Centre.
-
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