Date: Mon, 30 Aug 1999 14:53:12 +0200 (CEST) From: Wilko Bulte <wilko@yedi.iaf.nl> To: syssgm@detir.qld.gov.au (Stephen McKay) Cc: freebsd-current@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG, syssgm@detir.qld.gov.au Subject: Re: SCSI surprise! (was: Softupdates reliability?) Message-ID: <199908301253.OAA01384@yedi.iaf.nl> In-Reply-To: <199908300912.TAA00547@nymph.detir.qld.gov.au> from Stephen McKay at "Aug 30, 1999 7:12:15 pm"
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As Stephen McKay wrote ... > I took the lid off anyway hoping to find anything at all weird and noticed > something I had forgotten. I was using a Seagate ST51080N 1GB disk earlier > for some experimenting and had disconnected the POWER, but not the SCSI CABLE. > (It's a really noisy drive!) When I also unplugged the SCSI cable, all crashes > stopped. I've now used the machine intensively for several days (copying over > 20GB of small and big files, and read and written several tapes) without > incident. Conclusions: > > 4) My stepping of K6-2/300 is just fine > 5) My Exabyte really is ok :-) > 6) It is NOT safe to have a powered down SCSI device attached to a SCSI chain > 7) The world really is a wonderful place ;-) > > So, apart from being happy at having stable hardware again, I am intensely > curious about this. Why is a powered down SCSI device so nasty? For example, It is normally not so nasty. Did this particular device have the SCSI terminator? If so, the terminator needs +5V (terminator power aka TERMPWR) to function correctly. Some devices can be setup to take terminator power from the bus (generally supplied by the host adapter) or from the device they are installed on. I've run things with power-ed down devices without any ill effects. But always with external terminators, so not with the terminator on the device itself but on the bus cable. > the first crash locked up my SCSI card so that reset didn't fix it, and the > second crash hung one of my disks so that it had to be powered down to even > be recognised! Is there a standard for this stuff? Yes, the ANSI SCSI standard. www.t10.org (.com??) Wilko -- | / o / / _ Arnhem, The Netherlands - Powered by FreeBSD - |/|/ / / /( (_) Bulte WWW : http://www.tcja.nl http://www.freebsd.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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