Datastore missing – but Disk / Array detected?

I recently was playing around with ESXi and Removed my drives via the motherboard connections, tried another drive type and then tried to reconnect my orginal drive configuration. ( a non supported ICH9 controller, and Sata Drive )

I had no problem with the disk being detected upon a new rescan of LUN’s, but my data store did not show up.

Dave.Mishchenko pointed to page 117-118 of the ESX / ESXi iSCSI San Guide

VMFS Volume Resignaturing
ESX servers need to be able to differentiate between their VMFS volumes and use a
volume signature to do so. When a VMFS volume is replicated or a snapshot is taken,
the resulting LUN copy has the same signature as the source. When an ESX Server sees
two LUNs with the same signature, the ESX Server must handle the condition to
prevent downtime caused by confusion over which LUN it should be using to access
the registered virtual machines. Resignaturing is a feature introduced in ESX Server 3.0
to solve this problem.
Mounting Original, Snapshot, or Replica VMFS Volumes
You can mount original, snapshot, or replica VMFS volumes on the same ESX Server
To mount original, snapshot, or replica VMFS volumes
1 Perform the required storage tasks:
a Make the storage system snapshot or replica.
b Configure access control to allow ESX Server to access the snapshot or replica.
2 In the VI Client, select the host in the inventory panel.
3 Click the Configuration tab and click Advanced Settings.
4 Select LVM in the left panel, then set the LVM.EnableResignature option to 1.
5 Rescan for any new LUNs or VMFS volumes.
After the rescan, the copied VMFS volume appears as
If the VMX file for any of the virtual machines or the VMSD file for virtual machine
snapshots contains /vmfs/volumes/

This seemed to work great!

Thanks to Dave