How to have raid-based subcomponents autorun before a superset raid array (ie: RAID6+0 or RAID1+0/RAID10) in a multilevel/multilayer array setup: (It would be nice if the autodetect during boot would be intelligent about starting subarrays first, but it currently is not. It would not be that hard to code smart autodetection, or even easier (for the programmers), read some kernel command line parameters that allows the user to specify a manual start order. But for now, here's the way to fudge it.) Any array that is a superset of other arrays (a multilevel array) must set to non-autodetect. Use fdisk to change the parition type to 83 (standard linux), NOT "fd" (linux raid autodetect). That stops the kernel autodetect boot process on that array. Then, for Fedora Core (FC3 tested) add that array manually to /etc/mdadm.conf: #cat /etc/mdadm.conf DEVICE partitions ARRAY /dev/md5 UUID=9b3c3ca9:9637ed8a:4da282fe:63e5a3ab MAILADDR my@xxxxxxxxx (Get the UUID for the array with mdadm -D /dev/md5.) Then because of the mdadm call in /etc/rc.d/rc.sysinit (in FC at least), the higher-order array will get run automatically during the boot process but (hopefully) after the kernel autodetect (of the lower-order arrays) is done. This is tested working fine on FC3 at the following level: initscripts-7.93.7-1 kernel-2.6.12-1.1372_FC3 If your distro doesn't have a line in /etc/rc.d/rc.sysinit that calls "mdadm -As", then figure a way to add it to the boot process scripts early enough that it comes up just after RAID autodetection. If you aren't running any boot daemons off that array, it would probably be ok to start the array really late in the boot process like in rc.local. Note, the log output shows some interleaving of these commands so perhaps there may be a race condition and rc.sysinit may have to be modified to enforce a wait for the kernel autodetect to finish. So far this hasn't happened to me yet. (PS: Thanks guys for all your input.) - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
