From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Tokarev Subject: Re: Best Practice for Raid1 Root Date: Thu, 15 Jan 2004 03:32:12 +0300 Sender: linux-raid-owner@vger.kernel.org Message-ID: <4005DF8C.7080206@tls.msk.ru> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: To: Christian Kivalo Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Christian Kivalo wrote: >>Hi, >> > > [snip] > >>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. [] > one possible solution would be to use lilo. lilo is capable of booting > from md raid1 arrays. look at lilo.conf(5) manpage for 'raid-extra-boot' > in 'GLOBAL OPTIONS'. i use it on most of my maschines. AFAIK grub is not > able to boot from /dev/mdX. When using raid-extra-boot, lilo treats second disk as bios #0x81, 3rd disk as bios #0x82 and so on. That to say - if your first disk fails and BIOS will substitute second disk in place of first, making it 0x80 instead of 0x81, lilo will not boot too, exactly in a way why grub installed into /dev/hdb (that was e.g. temporarily plugged into another machine just to make it bootable etc) does not want to boot from it when it will be /dev/hda again (when returned back into it's own machine). Instead of using raid-extra-boot, IMHO, it is more safe to install lilo into the raid array instead of the MBR, and use standard MBR to boot from active partition. But granted, lilo's raid-extra-boot will work around different disk layouts, while lilo on raid with standard MBR will not. /mjt