Autostart RAID 1+0 (root)

Alok K. Dhir (alok@dhir.net)
Fri, 18 Jan 2002 11:40:55 -0500


Hey all - I may be trying to do the impossible here, but here goes:

I want to test using a software RAID 1+0 partition as root: md0 and md1
set up as mirrors between two disks each, and md2 set up as a stripe
between md0 and md1. However, the RedHat 7.2 installer doesn't allow
creating nested RAID partitions.

Being stubborn, I installed the OS onto a separate 4 gig disk, installed
all the latest patches+fixes to the OS, including the RH2.4.9-13 kernel,
then created md0, md1, and md2. I formatted md2 with reiserfs. No
problem so far.

Next, I copied the entire contents of the root partition onto md2,
changed the relevant line of /boot/grub/grub.conf from:

kernel /vmlinuz-2.4.9-13 ro root=/dev/sda2

To:

kernel /vmlinuz-2.4.9-13 ro root=/dev/md2

Changed fstab so "/" points to /dev/md2 as well, crossed my fingers, and
rebooted.

No luck. I get a "cannot mount root" error.

Attempting to speed read the boot messages before I get the panic, it
appears that md0 and md1 are autostarted, but it doesn't look like md2
is.

Does the kernel support autostarting nested RAID partitions?

Is doing software 1+0 a bad idea anyway due to performance issues?

Any ideas?

Thanks!

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/