I had a problem recently, and lost data on one of the RAID drives.When I reboot e-smith, the RAID system starting complainig, producing a lot of messages. After that, it started as usual, and everything was there. Then you have two choices.
First, and the one I did, reinstall e-smith (10 minutes) and restore a backup I had been making regularly; second, you can try to rebuild the RAID disk with the raid tools (ckraid, etc). In this case, I suggest having a look at the RAID HOWTOS, very helpfull.