From owner-freebsd-questions Thu Jul 5 8:11:49 2001 Delivered-To: freebsd-questions@freebsd.org Received: from mail.the-i-pa.com (mail.the-i-pa.com [151.201.71.132]) by hub.freebsd.org (Postfix) with SMTP id 9AF9C37B409 for ; Thu, 5 Jul 2001 08:11:43 -0700 (PDT) (envelope-from wmoran@iowna.com) Received: (qmail 84542 invoked from network); 5 Jul 2001 15:20:23 -0000 Received: from unknown (HELO iowna.com) (151.201.71.193) by mail.the-i-pa.com with SMTP; 5 Jul 2001 15:20:23 -0000 Message-ID: <3B4482DC.C3CF1B6C@iowna.com> Date: Thu, 05 Jul 2001 11:08:12 -0400 From: Bill Moran X-Mailer: Mozilla 4.76 [en] (X11; U; FreeBSD 4.2-RELEASE i386) X-Accept-Language: en MIME-Version: 1.0 To: Dale Hagglund Cc: freebsd-questions@freebsd.org, dnelson@emsphone.com Subject: Re: SCSI bad block remapping References: <3B327713.46173EC5@iowna.com> <863d8curun.fsf@ponoka.battleriver.com> <20010704205514.A13653@dan.emsphone.com> <86pubfubp7.fsf@ponoka.battleriver.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Dale Hagglund wrote: > > Dan Nelson writes: > > > In the last episode (Jul 04), Dale Hagglund said: > > > > (a) the disk might do remapping in fairly large chunks, even > > > up to a track in size, and > > > ... The couple drives I've looked at map single blocks. ... > > > > (b) after remapping, the data in the remapped region is > > > undefined. > > > I am extremely skeptical of this. If the data can be remapped, it > > is remapped correctly (that's what all the ECC stuff is for). If it > > cannot be remapped, an error is returned. > > Since this piqued my interest, I tracked down the horse's mouth. > According to the the SCSI-3 Block Commands specification, when a > REASSIGN BLOCKS command is issued the data contained in blocks being > remapped may be modified. Also, the command can fail because it needs > to remap a larger region than the one specified. However, from the > documentation of AWRE and ARRE, it appears that blocks are reassigned > automatically only if the drive firmware can recover the data. > > It looks like the upshot is that you can, as you suggested, turn on > automatic sector remapping without fear of silent data loss. This is good to know. Thank you for taking the time to look into the specs for us, Dan. Now that I know that it is safe to turn on sector remapping, I still don't know _how_ to do it. I'm also still curious about what's going on with a drive that crashes because of bad sectors one day, and then (once reformatted) runs with no problems for over a week (and still running ...) Thanks so far, Bill To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message