From owner-freebsd-hackers Fri Dec 8 17:06:07 1995 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id RAA10525 for hackers-outgoing; Fri, 8 Dec 1995 17:06:07 -0800 (PST) Received: from phaeton.artisoft.com (phaeton.Artisoft.COM [198.17.250.211]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id RAA10519 for ; Fri, 8 Dec 1995 17:06:01 -0800 (PST) Received: (from terry@localhost) by phaeton.artisoft.com (8.6.11/8.6.9) id SAA00728; Fri, 8 Dec 1995 18:05:06 -0700 From: Terry Lambert Message-Id: <199512090105.SAA00728@phaeton.artisoft.com> Subject: Re: Hint's needed for debugging a SCSI CDROM changer problem. To: truesdel@nas.nasa.gov Date: Fri, 8 Dec 1995 18:05:06 -0700 (MST) Cc: hackers@FreeBSD.ORG In-Reply-To: <8125.818467675@nas.nasa.gov> from "Dave Truesdell" at Dec 8, 95 04:07:55 pm X-Mailer: ELM [version 2.4 PL24] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hackers@FreeBSD.ORG Precedence: bulk > I've been attempting to get a SCSI CDROM changer working FreeBSD 2.1(-stable). > The device a Mountain "CD7" (aka. NRC MBR-7). I can mount and access the first > four CDROM's without any problems. However, when I attempt to mount the 5th > CDROM I soon get either (what appears to be) a hung SCSI bus, or I get "Fatal > trap 12"'s in random parts of the kernel. (Two crashes I've saved had the > faults occur in both the isofs and vm code.) On a hunch: can you disable tagged command queueing and/or SCSI detach for the device? Perhaps the problem is that an outstanding operation from the previous disk is hanging out there. Also try accessing one disk, then another, then waiting for 30 seconds to a minute. Repeat a couple of times. In any case, the disabling of async command completion might fix it for you. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.