Date: Fri, 21 Apr 1995 18:33:30 +1596657 (MET DST) From: Wilko Bulte <wilko@yedi.iaf.nl> To: dufault@hda.com (Peter Dufault) Cc: terry@cs.weber.edu, pritc003@maroon.tc.umn.edu, rgrimes@gndrsh.aac.dev.com, hackers@freefall.cdrom.com Subject: Re: [DEVFS] your opinions sought! Message-ID: <199504211633.SAA01248@yedi.iaf.nl> In-Reply-To: <199504211356.JAA16639@hda.com> from "Peter Dufault" at Apr 21, 95 09:56:52 am
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> > Yuck! Powering up/down for SCSI devices on the fly is generally a > > sure way to hang the buses, screw the disks etc. It *should* work, > > but my experience shows that it has something like a 20% chance to > > bomb. > > This is true, though with practice you only have to restore your > disks once a year. We still have a nasty bug someplace that results in > unending disk timeouts and eventual system death. Usually, though > our disk drivers I've also seen 'adapter frozen' or something similar on AH154x cards. Is this what you mean? > will redo a transfer that was in progress when a device powered up on > the bus, assuming the disk drive properly detects the power up. That's the way it should work yes. Don't count on all hostadapters to keep their act together though ;-) > A utility that suspends all activity on the SCSI bus will make powering > up a device safe, though, and I've been thinking of doing it (suspend > activity, beep when all activity is suspended, delay for 10 seconds, and > permit activity to resume). Should work fine. The raidsystems I use at work (==DEC) use a similar approach to 'hotswap' drives. While we are at it: the 'scsi' tool reputedly should allow a re-probe of all devices. What is the exact syntax for this? The man page is less than obvious to me (this is _still_ 1.1.5, I need stability more than features (...)) > Peter Dufault Real Time Machine Control and Simulation _ __________________________________________________________________________ | / o / / _ Wilko Bulte email: wilko@yedi.iaf.nl |/|/ / / /( (_) Private FreeBSD site - Arnhem - The Netherlands --------------------------------------------------------------------------------
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