From owner-freebsd-scsi Tue Oct 13 00:22:35 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id AAA13178 for freebsd-scsi-outgoing; Tue, 13 Oct 1998 00:22:35 -0700 (PDT) (envelope-from owner-freebsd-scsi@FreeBSD.ORG) Received: from gatekeeper.tsc.tdk.com (gatekeeper.tsc.tdk.com [207.113.159.21]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id AAA13172; Tue, 13 Oct 1998 00:22:34 -0700 (PDT) (envelope-from gdonl@tsc.tdk.com) Received: from sunrise.gv.tsc.tdk.com (root@sunrise.gv.tsc.tdk.com [192.168.241.191]) by gatekeeper.tsc.tdk.com (8.8.8/8.8.8) with ESMTP id AAA23196; Tue, 13 Oct 1998 00:22:16 -0700 (PDT) (envelope-from gdonl@tsc.tdk.com) Received: from salsa.gv.tsc.tdk.com (salsa.gv.tsc.tdk.com [192.168.241.194]) by sunrise.gv.tsc.tdk.com (8.8.5/8.8.5) with ESMTP id AAA02758; Tue, 13 Oct 1998 00:22:15 -0700 (PDT) Received: (from gdonl@localhost) by salsa.gv.tsc.tdk.com (8.8.5/8.8.5) id AAA14971; Tue, 13 Oct 1998 00:22:13 -0700 (PDT) From: Don Lewis Message-Id: <199810130722.AAA14971@salsa.gv.tsc.tdk.com> Date: Tue, 13 Oct 1998 00:22:12 -0700 In-Reply-To: "Justin T. Gibbs" "Re: filesystem safety and SCSI disk write caching" (Oct 13, 12:59am) X-Mailer: Mail User's Shell (7.2.6 alpha(3) 7/19/95) To: "Justin T. Gibbs" , Terry Lambert Subject: Re: filesystem safety and SCSI disk write caching Cc: Don.Lewis@tsc.tdk.com, julian@whistle.com, freebsd-fs@FreeBSD.ORG, freebsd-scsi@FreeBSD.ORG Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Oct 13, 12:59am, "Justin T. Gibbs" wrote: } Subject: Re: filesystem safety and SCSI disk write caching } I'm still unclear as to whether Don was turning off power or hitting what I } consider the reset button. His comment about UPSes use makes me think he } was testing power outage scenarios. I was hitting the reset button to test the softupdates code because I thought that write caching on the drive was disabled. It wasn't until I got the unexpected filesystem inconsistency that I actually checked the state of the write caching bit. Once I disable write caching, I didn't get any more unexpected inconsistencies, though I didn't repeat this experiment enough to totally convince myself that my results were conclusive. With write caching disabled, I'd expect the same results with either the reset button or the power switch, but I didn't test the latter since it's a lot rougher on the hardware. If the inconsistency was due to a missing softupdates dependency, I'd expect to see more inconsistencies in the many panics I provoked in some other testing I was doing. With the exception of some inconsistencies created by bugs in fsck that corrupted the filesystem while attempting to fix it, I did not see any unexpected inconsistencies caused by these panics. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message