Hi, I have been playing with booting from Raid5 and managed to hack together a fix for the grub-setup to make grub install correctly on Raid5 disk sets. It's not pretty yet but it worked for installing onto a raid5 whole disk set and having it boot. I will start creating a proper set of patches to submit soon.
This boots fine except for the partition table that the kernel sees on 1st disk is for the size of the whole raid volume, and complains about trying to access beyond the end of the device until the kernels raid driver starts up and assembles the array. Another problem with booting of a raid 5 diskset is that if the first disk is not available then we can't boot. This is because the only bootsector and partition table is on the first disk in the set. (One can recover it from the parity disk once we've got the degraded array assembled, but we can't boot unless we can read the bootsector and assemble the raid array.) I have proposed the below solution to the linux-raid mailing list as a solution for booting from software raid levels 4/5/6/10 using grub2. The first cylinder which needs to be mirrored across all the devices, would be for the Volume/Master Boot record + Boot Sector Code. Grub2 bootsector + core.img should fit in here at (or least enough of it to bring grub up with the appropriate raid drivers required to assemble the array.) We could include a dummy partition table with the whole disk in the 1st partition labeled as something like linux-raid (0xfd) or Non-FS data (0xda). The second cylinder has the md superblock and write intent bitmap, and the raid volume starts at the beginning of the 3rd cylinder, starting with a normal mbr/partition table for this raid volume. Let me know what you think of this scheme. Regards, -- Daniel Reurich Centurion Computer Technology (2005) Ltd Ph 021 797 722 _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
