Same problem with PowerEdge R420.
Reinstalled with Dell customized ESXi 5.1, no change. Then found this thread.
1. SSH
2. fdisk -l
- Fdisk shows that it is deprecated, use partedUtil instead.
3. partedUtil delete <diskName> <partNum>
- I ran this on both (1 and 2) partitions. SD has 5 partitions instead of just two.
This solved the problem.