From mboxrd@z Thu Jan 1 00:00:00 1970 From: Terrence Martin Subject: Best Practice for Raid1 Root Date: Wed, 14 Jan 2004 15:43:04 -0800 Sender: linux-raid-owner@vger.kernel.org Message-ID: <4005D408.8060002@physics.ucsd.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi, I wanted to post this question for a while. On several systems I have configured a root software raid setup with two IDE hard drives. The systems are always some version of redhat. Each disk has its own controller and is partitioned similar to the following, maybe with more partitions, but this is the minimum. hda1 fd 100M hda2 swap 1024M hda3 fd 10G hdc1 fd 100M hdc2 swap 1024M hdc3 fd 10G The Raid devices would be /dev/md0 mounted under /boot made of /dev/hda1 and /dev/hdc1 /dev/md1 mounted under / made of /dev/hda3 and /dev/hdc3 The boot loader is grub and I want both /boot and / raided. In the event of a failure of hda I would like the system to switch to hdc. This works fine. However what I have had problems with is if the system reboots. If /dev/hda is unavailable I no longer have a disk with a boot sector set up correctly. Unless I have a floppy or CDROM with a boot loader the system will not come up. So my main question is what is the best practice to get a workable boot sector on /dev/hdc? How are other people making sure that their system remains bootable after a disk failure of the boot disk? Is it even possible with software raid and PC BIOS? Also when you replace /dev/hda how are you getting a valid boot sector on that disk? I have found grub to often be problematic so that even when I move the good drive to be hda grub does not like to install itself correctly. I am sure I am approaching this incorrect in some way, I am just not sure what is the right way. Terrence Martin UCSD Physics