Date: Tue, 31 Aug 1999 19:52:55 +1000 From: Stephen McKay <syssgm@detir.qld.gov.au> To: Wilko Bulte <wilko@yedi.iaf.nl> Cc: freebsd-scsi@FreeBSD.ORG, syssgm@detir.qld.gov.au Subject: Re: SCSI surprise! (was: Softupdates reliability?) Message-ID: <199908310952.TAA18445@nymph.detir.qld.gov.au> In-Reply-To: <199908301253.OAA01384@yedi.iaf.nl> from Wilko Bulte at "Mon, 30 Aug 1999 14:53:12 %2B0200" References: <199908301253.OAA01384@yedi.iaf.nl>
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On Monday, 30th August 1999, Wilko Bulte wrote: >As Stephen McKay wrote ... > >> 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. Just to be more clear about this: The SCSI cable has an active terminator on the end, so no devices are terminated. The problem drive is not terminated and functions just fine when powered up. It is in the middle of the chain. I've had other powered-down-but-connected SCSI devices without trouble in the past. I'll check the drive more carefully tonight for "power terminator from BUS" stuff to see if there is any possible silly stuff there. But I think the fact is that sometimes it's not safe to just pull the power plug. Stephen. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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