From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: switching root fs '/' to boot from RAID1 with grub Date: Thu, 01 Nov 2007 11:57:24 -0700 Message-ID: <472A2194.9070408@zytor.com> References: <20071030210721.386ca2fa@absurd> <1193781699.10336.585.camel@firewall.xsintricity.com> <472A0D7A.4040807@zytor.com> <1193941858.10336.659.camel@firewall.xsintricity.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1193941858.10336.659.camel@firewall.xsintricity.com> Sender: linux-raid-owner@vger.kernel.org To: Doug Ledford Cc: Janek Kozicki , linux-raid@vger.kernel.org List-Id: linux-raid.ids Doug Ledford wrote: > > Correct, and that's what you want. The alternative is that if the BIOS > can see the first disk but it's broken and can't be used, and if you > have the boot sector on the second disk set to read from BIOS disk 0x81 > because you ASSuMEd the first disk would be broken but still present in > the BIOS tables, then your machine won't boot unless that first dead but > preset disk is present. If you remove the disk entirely, thereby > bumping disk 0x81 to 0x80, then you are screwed. If you have any drive > failure that prevents the first disk from being recognized (blown fuse, > blown electronics, etc), you are screwed until you get a new disk to > replace it. > What you want is for it to use the drive number that BIOS passes into it (register DL), not a hard-coded number. That was my (only) point -- you're obviously right that hard-coding a number to 0x81 would be worse than useless. -hpa