Rebalance can leave devices in "drain" mode, causing errors in the system during FSCK

```

mogadm should warn that there are devices stuck in "drain" mode.   This can 
happen if a rebalance is stopped and reset.   

mogadm should either warn, or set, devices that have been left in "drain" mode 
back to active mode.




```

Original issue reported on code.google.com by `martinb...@gmail.com` on 9 Jul 2012 at 6:37
