I had a core/md and two diskless MD's running and then upgraded to Beta4. Since then I have reinstalled the diskless MD the following two problems. First, I had to reinstall the diskless MD's and each required several tries but finally succeeded. Secondly, when I shut down the diskless MD's and tried to restart them each will time out. I have deleted them several times reinstalled with some failures and retries and finally got them to install again. After turning them off, once again they will time out.
please update to RC1 and report back.