hi,

from my experience you should start failover, never work with open-e storage thats rebuild. shutdown the primary and do the rebuild within the bios setup of your controller.
after that start open-e on the primary and start resync. if there are any errors you must clear the metadata on the primary and to a full sync.

i had very very bad experience with rebuild on open-e with adaptec and raid6...
have a look at this thread
http://forum.open-e.com/showthread.php?t=1991

and this error still exist in open-e/adaptec! and should be fixed in one of the next releases...

greetings
roger