Hi Jan, Many thanks for your help, it works fine. I created the entries in /etc/mdadm.conf by mdadm --examine --scan >> /etc/mdadm.conf But unfortunately this command creates only the ARRAY entries, the DEVICE entries are missing (DEVICE partitions was created by anaconda) and as you told me the entry "DEVICE /dev/md11 /dev/md12" is essential. In the meanwhile I tested another way to get a RAID10 array by creating a RAID1 arrays with mdadm and a RAID0 array on top of the RAID1 arrays by lvm, this works fine on reboot without any special entries in configuration files: vgcreate -s 4M VGu0102 /dev/md11 /dev/md12 lvcreate --stripes 2 --stripesize 64 -size 30G -name LVu01 VGu0102 lvcreate --stripes 2 --stripesize 32 -size 100G -name LVu02 VGu0102 An advantage of lvm striping is to use different stripesizes for the logical volumes. Did you ever test RAID10 with md/lvm? What are your experencies? Again thanks and best regards Peter Dr. Peter Stauffert Boehringer Ingelheim Pharma GmbH & Co. KG e-mail: [log in to unmask] -----Ursprüngliche Nachricht----- Von: Jan vandenBerg [mailto:[log in to unmask]] Gesendet: Samstag, 11. November 2006 00:23 An: Stauffert,Dr.,Peter (ALF) BIP-DE-B Cc: [log in to unmask] Betreff: Re: Raid10 with SL 4.2 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] > > >