Hi, Peter. I think the problem is that the raid system looks for raid devices in 'DEVICE partitions' by default as it's auto-detecting arrays. But you need it to also look in some raid devices themselves for another array. Here's an /etc/mdadm.conf from one of our systems with a raid10 defined. In this case, md6 is the raid10, and md[4,5] are the sub-mirrors. The key lines for autodetecting the raid10 at boot are the 'DEVICE /dev/md4 /dev/md5' and the 'ARRAY /dev/md6 ...' one. The UUID, or some other identifying information, can be had IIRC via something like: mdadm --misc --query --detail /dev/md6 That assumes that the array is started, though. If you've lost it via a reboot and can't get it back online, I think you can do something like: mdadm --misc --examine /dev/md4 (note that in the --examine case we're looking at one of the sub-mirrors). DEVICE partitions DEVICE /dev/md4 /dev/md5 ARRAY /dev/md0 super-minor=0 ARRAY /dev/md3 super-minor=3 ARRAY /dev/md2 super-minor=2 ARRAY /dev/md1 super-minor=1 ARRAY /dev/md4 super-minor=1 ARRAY /dev/md5 super-minor=1 ARRAY /dev/md6 level=raid0 num-devices=2 UUID=86c93314:62a7eba4:a1a8b392:72f89a69 devices=/dev/md4,/dev/md5 -Jan On Fri, 10 Nov 2006 [log in to unmask] wrote: > Date: Fri, 10 Nov 2006 19:56:43 +0100 > From: [log in to unmask] > To: [log in to unmask] > Subject: Raid10 with SL 4.2 > > Hi, > > I created a RAID10 out of 2 RAID1 arrays on a SL4.2 system with SCSI disks: > mdadm --create --force /dev/md11 --verbose --level=raid1 --raid-devices=2 > /dev/sdb1 /dev/sdi1 > mdadm --create --force /dev/md12 --verbose --level=raid1 --raid-devices=2 > /dev/sdc1 /dev/sdj1 > mdadm --create --force /dev/md10 --verbose --chunk=64 --level=raid0 > --raid-devices=2 /dev/md11 /dev/md12 > This RAID10 array is assembled and usable, but when I reboot the system, only > the underlying RAID1 arrays are assembled, the RAID10 array is not. > > Can anybody help me? > > Best regards > > Peter > > Dr. Peter Stauffert > Boehringer Ingelheim Pharma GmbH & Co. KG > e-mail: [log in to unmask] > > >