Date: Tue, 27 Feb 1996 13:45:07 +0100 From: se@zpr.uni-koeln.de (Stefan Esser) To: "Justin T. Gibbs" <gibbs@freefall.freebsd.org> Cc: Dave Andersen <angio@aros.net>, questions@freebsd.org Subject: Re: Ncr scsi: overlapped commands attempted Message-ID: <199602271245.AA29271@Sysiphos> In-Reply-To: "Justin T. Gibbs" <gibbs@freefall.freebsd.org> "Re: Ncr scsi: overlapped commands attempted" (Feb 26, 22:31)
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On Feb 26, 22:31, "Justin T. Gibbs" wrote: } Subject: Re: Ncr scsi: overlapped commands attempted } >On Feb 23, 19:10, Dave Andersen wrote: } >} Subject: Ncr scsi: overlapped commands attempted } >} I'm wondering if anyone could lend me a quick clue here. When I boot } >} up, I get: } >} } >} ABORTED COMMAND asc:4e,0 Overlapped commands attempted } >} } >} from an HP 2gb SCSI drive. This happens under both -release and } >} -current. I'd prefer to run -release or -stable on this machine. } >} } >} Any suggestions? } > } >Yes: Switch off tagged commands ... :( } > } >The HP drive is known to cause problems } >when used with tagged commands. The problem } >is diagnosed, but the solution isn't obvious, } >yet ... } > } } The only thing that comes to mind is that an untagged request } sense command is pending when another tagged command is queued } to the target. The aic7xxx driver never tagges request sense commands } since the spec dictates that they must be untagged (and some drives } choke on this) and it also gurantees that no other commands are posted } to the target until the request sense completes successfully. Yes, I know about this, and teh NCR driver makes sure that no tags are used with REQUEST SENSE commands. The HP drive problems are most likely caused by several tagged START STOP UNIT commands being sent to the drive. Most drives do the right thing (i.e. ignore a start unit if the motor is running :), but a few seem to perform a soft reset and don't tolerate several of these commands being active at a time. The GENERIC SCSI code calls scsi_start_unit() whenever a raw disk partition is opened, and two programs do several opens within a millisecond: FSCK and DUMP. I've been thinking about sending only teh first start unit to each LUN, but for now I think the generic SCSI code should NOT issue them in the first place for EACH open. Regards, STefan -- Stefan Esser, Zentrum fuer Paralleles Rechnen Tel: +49 221 4706021 Universitaet zu Koeln, Weyertal 80, 50931 Koeln FAX: +49 221 4705160 ============================================================================== http://www.zpr.uni-koeln.de/~se <se@ZPR.Uni-Koeln.DE>
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