On 02/12/2011 09:00 AM, Gerhard Schneider wrote: > > Sorry, I don't use CentOS 6 now so I cannot check, but: > > Could it be that RHEL6 changed the default superblock mdadm is creating? > CentOS 5 is creating a 0.9 superblock. Some "other OS" are creating 1.2 > per default. But you can change that on the command line. > > If that's the case it's not a bug but a feature.. > > GS > > -- Gerhard Schneider Institute of Lightweight Design and e-Mail: > gs at ilsb.tuwien.ac.at Structural Biomechanics (E317) Tel.: +43 664 60 588 > 3171 Vienna University of Technology / Austria Fax: +43 1 58801 31799 > A-1040 Wien, Gusshausstrasse 27-29 http://www.ilsb.tuwien.ac.at/~gs/ Bingo! That hadn't occurred to me. And 1.2 is specified in the mdadm.conf file, which went right over my head. :-( Thanks Gerhard; mystery solved. Now all I need to do is wait for CentOS-6 to see if it correctly assembles all members of the arrays at boot time. I suspect the evaluation copy of RHEL-6 is not really up to date, so there may be issues with mdadm. I did take a look around the RedHat bugzilla site and saw a couple of things that might be related to the problem. Chuck