From owner-freebsd-geom@FreeBSD.ORG Wed Aug 16 12:50:57 2006 Return-Path: X-Original-To: freebsd-geom@FreeBSD.org Delivered-To: freebsd-geom@FreeBSD.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C88F216A4DE for ; Wed, 16 Aug 2006 12:50:57 +0000 (UTC) (envelope-from arne_woerner@yahoo.com) Received: from web30312.mail.mud.yahoo.com (web30312.mail.mud.yahoo.com [209.191.69.74]) by mx1.FreeBSD.org (Postfix) with SMTP id 85B9343D49 for ; Wed, 16 Aug 2006 12:50:56 +0000 (GMT) (envelope-from arne_woerner@yahoo.com) Received: (qmail 85638 invoked by uid 60001); 16 Aug 2006 12:50:55 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=0/M4uCh43DfgemFn1NxEnJVvITM/MUn9W0DbU7wjYTHHNjcfIGPO31OD7OOqmyjkv9hgW9pxmva1f1AAd97h3UDReCjVRuBVVykZwA6Hc6EOZV17XvxKSD3NetROVSRLAKxETM2Fitavof02HfqWTYsMS98/CrICCpVVgQD2kdA= ; Message-ID: <20060816125055.85636.qmail@web30312.mail.mud.yahoo.com> Received: from [213.54.79.182] by web30312.mail.mud.yahoo.com via HTTP; Wed, 16 Aug 2006 05:50:55 PDT Date: Wed, 16 Aug 2006 05:50:55 -0700 (PDT) From: "R. B. Riddick" To: Danny Carroll , freebsd-geom@FreeBSD.org In-Reply-To: <44E30387.5000203@dannysplace.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: Subject: Re: Mirror MBR? X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Aug 2006 12:50:57 -0000 --- Danny Carroll wrote: > My main question is about the MBR. I dont see anywhere in the doc where > I should put a new boot record on the disk after doing: > If u mirror the whole disk (solution 1) the first sectors should be mirrored like the others (but not the last, which contains disk specific meta data). > dd if=/dev/zero of=/dev/ad0 bs=512 count=79 > What is that good for? Doesn't gmirror synchronize automatically? > Does this mean that the MBR from the mirror gets put onto this first disk? > During boot stages gmirror is not known. All boot programmes (BIOS, stage1, stage2, stage3) use the data on the first sectors of the disk, slice and/or partition) for booting... When the system mounts the root file system gmirror is needed and used if proper configured (that would be: gmirror module loaded before boot or compiled to kernel). > I ask because, I need to know what should happen when I need to replace > a disk. > If I were u, I would simulate all (or the imporant) scenarios: E. g.: 1. One disk failed while power is off... 2. One disk is added while power is off... 3. One disk recovers after power on (e. g. after a power failure, which corrupted the mirror)... If you are really busy as a bee, you could try putting a geom_nop device into the mirror and see, what happens if u suddenly configure the nop-disk to behave like a really bad disk... :-) > I know that after replacing the disk I should probably have to do > something like this: (Assume ad0 is the new disk) > > gmirror configure -a gm0 > What is that good for? I run my geom_mirrors always in AUTO_SYNC mode... E. g. in case of a power failure or so... > But does that guarantee me that if ad0 fails, then I still have a > bootable system (assuming bios knows to boot of ad1). > Yes, it should. At least if the BIOS is smart enough to look for another disk if the first one mentioned in BIOS configuration behaves like a dead disk... I tested it on my box and I think, that it worked fine... <-- this was no sworn testimony... -Arne --- Arne likes "Kentucky Fried Movie" (especially "A fistful of yen") :-) __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com