Return to BSD News archive
Newsgroups: comp.unix.bsd.bsdi.misc,comp.sys.hp.hardware
Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.rmit.EDU.AU!news.unimelb.EDU.AU!munnari.OZ.AU!news.ecn.uoknor.edu!news.cis.okstate.edu!newsfeed.ksu.ksu.edu!news.physics.uiowa.edu!math.ohio-state.edu!howland.reston.ans.net!vixen.cso.uiuc.edu!newsfeed.internetmci.com!usenet.eel.ufl.edu!col.hp.com!news.dtc.hp.com!hplntx!hplb!hpcpb!kev
From: kev@bri.hp.com (Kevin Jones)
Subject: Re: HP C1533A DDS-2 SCSI Tape Drive Hangs
Sender: news@bri.hp.com (News User)
Message-ID: <DsMnxr.KEL@bri.hp.com>
Date: Fri, 7 Jun 1996 11:29:51 GMT
References: <4p1k7f$9b6@news.inforamp.net>
Nntp-Posting-Host: pute.bri.hp.com
Organization: Hewlett-Packard
X-Newsreader: TIN [version 1.2 PL1.4]
Followup-To: comp.unix.bsd.bsdi.misc,comp.sys.hp.hardware
Lines: 57
Xref: euryale.cc.adfa.oz.au comp.unix.bsd.bsdi.misc:3953 comp.sys.hp.hardware:15604
markjr@shmooze.net (markjr@shmooze.net) wrote:
: Anyone know about these Tape Drives or SCSI drives (external) in
: general? The system sees the drive fine, but after an arbirtrary
: amout of reading or writing, the whole box hangs.
Hanging during reads/writes is often due to a low integrity SCSI bus.
: Not overly familiar with SCSI buses, would changing the SCSI ID
: (currently 4) impact this kind of thing? (I can't see any conflicts),
: what about the bios settings (most of them sutiably tweaked to deal
: with the internal SCSI bus). The drive is external, so I disabled
: the bios termination. I believe the external terminator is a "passive"
: one. Would the external drive have a different SCSI controller ID than
: the internal? At the moment they're all on 0. Hmmm.
A few rules on SCSI busses:
T-------------------------------------------T
| | |
7 4 0
T=Terminator. One should be fitted at each end. Active terminators
are preferable to passive ones. Short busses (eg. < 3 meters) with
light loading might work with passive terminators. Long and/or heavily
loaded busses should use active termination. Having too few terminators
(eg. only terminating one end of the bus) or too many terminators
will result in either immediate hangs or intermittent hangs.
Overall bus length should not exceed 6 meters. Preferably, it should
be less than 3 meters. Lengths of cable stubbs off the main bus
should not exceed 10cm.
Each device on the bus must have a unique ID. Normally, the host
interface is wired to ID 7 and internal drives 0,1,2.... etc.
Good quality cables should be used (eg. screened twisted pair).
Unfortunately there is a lot of junk on the market and it can
be difficult to spot the difference.
Some PC host bus adapters allow you to configure synchronous transfer
rates. It is often possible to "fix" a SCSI bus by limiting transfer
speeds to 5MHz or less.
-----------------------------------------------------------------
Kevin Jones. | Hewlett Packard Ltd,
| Computer Peripherals Bristol,
kev@bri.hp.com | Filton Road,
| Stoke Gifford,
| Bristol. BS12 6QZ.
| ENGLAND.
-----------------------------------------------------------------
This response does not represent the official position of, or
statement by, the Hewlett-Packard Company. The above data is
provided for informational purposes only. It is supplied
without warranty of any kind.