Device Extent and ESX Partition Issue

[mnetwork]

Today I attempted to upgrade my NAS from 8.0.2 to 8.2.0. During the process I thought I messed up the USB drive where FreeNAS resided so I decided start completely from scratch on 8.0.2 again (long story). After I did, I added my iSCSI setup back by recreating my one Device Extent again. I re-scanned after I reconfigured everything and the three ESX hosts could see the storage, but did not recognize it as a VMFS volume. I looked around and it looked like the partition table needed to be recreated, I did not want to take a chance and do this myself so I put in a support ticket with VMware. The tech wound up creating the partition table through the CLI and all was well after this. My question is, why did I have to do this? Does the partition table of a Device Extent get stored in the FreeNAS configuration database on the USB drive? I would really like to understand why this happened.

My setup

Dell PowerEdge 830
Builtin Controller with 4 drives running one RAID 10 logical volume
FreeNAS 8.0.2
One iSCSI Device Extent
Three ESX5 hosts in a cluster