From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: RAID1 root and swap and initrd Date: Thu, 21 Dec 2006 13:47:35 -0500 Message-ID: <458AD6C7.80405@tmr.com> References: <20061215175630.GA11400@aym.net2.nerim.net> <20061216210517.GB11400@aym.net2.nerim.net> <45846A43.8070207@tls.msk.ru> <45885A06.6070100@tmr.com> <458A9E07.2040608@tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <458A9E07.2040608@tls.msk.ru> Sender: linux-raid-owner@vger.kernel.org To: Michael Tokarev Cc: Andre Majorel , linux-raid@vger.kernel.org List-Id: linux-raid.ids Michael Tokarev wrote: > [A late follow-up] > > Bill Davidsen wrote: > >> Michael Tokarev wrote: >> >>> Andre Majorel wrote: >>> [] >>> >>> >>>> Thanks Jurriaan and Gordon. I think I may still be f*cked, >>>> however. The Lilo doc says you can't use raid-extra-boot=mbr-only >>>> if boot= does not point to a raid device. Which it doesn't because >>>> in my setup, boot=/dev/sda. >>>> >>>> Using boot=/dev/md5 would solve the raid-extra-boot issue but the >>>> components of /dev/md5 are not primary partitions (/dev/sda5, >>>> /dev/sdb5) so I don't think that would work. >>>> >>> So just move it to sda1 (or sda2, sda3) from sda5, ensure you've >>> two identical drives (or at least your boot partitions are layed >>> up identically), and use boot=/dev/md1 (or md2, md3). Do NOT >>> use raid-extra-boot (set it to "none"), but set up standard mbr >>> code into boot sector of both drives (in debian, it's 'mbr' package; >>> lilo can be used for that too - once for each drive), and mark your >>> boot partition on both drives as active. >>> >>> This is the most clean setup to boot off raid. You'll have two >>> drives, both will be bootable, and both will be updated when >>> you'll run lilo. >>> >>> Another bonus - if you'll ever install a foreign OS on this system, >>> which tends to update boot code, all your stuff will still be intact - >>> the only thing you'll need to do to restore linux boot is to reset >>> 'active' flags for your partitions (and no, winnt disk manager does >>> not allow you to do so - no ability to set non-dos (non-windows) >>> partition active). >>> >>> >>>> I *could* run lilo once for each disk after tweaking boot= in >>>> lilo.conf, or just supply a different -M option but I'm not sure. >>>> The Lilo doc is not terribly enlightening. Not for me, anyway. :-) >>>> >>> No, don't do that. Even if you can automate it. It's error-prone >>> to say the best, and it will bite you at an unexpected moment. >>> >> The desirable solution is to use the DOS MBR (boot active partition) and >> put the boot stuff in the RAID device. However, you can just write the >> MBR to the hda and then to hdb. Note that you don't play with the >> partition names, the 2nd MBR will only be used if the 1st drive fails, >> and therefore at the BIOS level the 2nd drive will now be hda (or C:) if >> LILO stiff uses the BIOS to load the next sector. >> > > Just a small note. DOS MBR can't boot from non-primary partition. > In this case, the boot code is at sda5, which is on extended partition. > > But. Lilo now has ability to write its own MBR, which, in turn, IS > able to boot of logical partition. > > lilo -M /dev/sda ext > > Useful if you can't use a primary for /boot for some reason. grub can do this as well, of course. -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979