Raid array is not automatically detected.

Hi Bryan,
I was just having the same problem and the mdadm man page clearly states:
----------------------------
--homehost=
This will override any HOMEHOST setting in the config file and provides the
identity of the host which should be considered the home for any arrays.

When creating an array, the homehost will be recorded in the superblock.
For version-1 superblocks, it will be prefixed to the array name. For version-0.90 superblocks, part of the SHA1 hash of the hostname will be stored in the later half of the UUID.

When reporting information about an array, any array which is tagged for
the given homehost will be reported as such.

****
When using Auto-Assemble, only arrays tagged for the given homehost will be
assembled.
****
----------------------------

So just once stop your array and manually assemble it like
mdadm -A <md-device> <components> --homehost=<somestring> --update=homehost and from the next reboot on, that array, too, will automatically be assembled by the linux kernel.
HTH
Daniel

thanks for the tip!