Messages in this thread | | | Subject | Re: booting RAID partitions | Date | Sat, 29 Aug 1998 16:03:53 -0400 (EDT) | From | Jeff Garzik <> |
| |
You wrote: > On 26 Aug 1998 17:43:19 -0700, MOLNAR Ingo <mingo@chiara.csoma.elte.hu> > wrote: > >there is a trick though: to allocate a large enough file and determine > >where the contents map to, and pick out the blocks belonging to the target > >disk(s). Then the image can be scattered across those blocks and fed to > >lilo's chainloader. The image will only be on that disk. (the real image > >file will be a big file, sparsely containing the real image)
[fmt'd accidentally] > Actually, I'd suggest something slightly better: Instead of writing > kernel chunks only on the first disk, those chunks may as well be > written on each disk, and you'd end up with a complete bootable > kernel on each disk. The advantage is that if you loose a disk in > a Raid 4/5 configuration, you still have a working kernel on each > of the other disks, and you can still boot in degraded mode.
This solution seems the best of all that I've heard so far. Reserve a certain amount of space at the beginning of every partition included in a metadisk; 2 MB? A kernel and initrd image (if any) are copied into each component partition, in that first 1-2MB reserved space.
Then booting off a metadisk is simple. Just list the component partitions on the kernel command line, line
append = "md-root=linear,/dev/sda1,/dev/sdb1,/dev/sdc1" or append = "md-root=raid1+0,/dev/sda1,/dev/sdb1,/dev/sdc1,/dev/sdd1" or append = "md-root=raid5,/dev/sda1,/dev/sdb1,/dev/sdc1" or append = "md-root=raid1,/dev/sda1,/dev/sdb1" ...
md yanks the kernel and initrd off the first partition it finds.
Installation is even easy... :)
cat vmlinux.gz initrd.img.gz > mdimage dd if=mdimage of=/dev/sda1 bs=1024k # md part 1/3 dd if=mdimage of=/dev/sdb1 bs=1024k # md part 2/3 dd if=mdimage of=/dev/sdc1 bs=1024k # md part 3/3
You probably want to MD5-sum the 2MB kernel/initrd space and write disk offsets, so the above example is a simplification.
How does that sound?
Jeff
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.altern.org/andrebalsa/doc/lkml-faq.html
| |