Let's start from the beginning. Two ESXi 4.0.0 hosts running Windows 2008 Virtual Machines (one on each). On VM1/Host1 I created a bunch of RDM disks, 14 to be precise. LUNs obviously reside in the SAN with every LUN presented to both of our hosts with the same LUN #. Then I proceeded to add those same disks to the VM2 running under Host2, using the existing disks from Host1's VM. After that I configured the VMs to run Windows Clustering+SQL2008, which is working fine.

I've been booting the VM's and the Hosts to see how it all works. I've had no problems, until now.

My next test was fatal for the system. I unplugged Host1 from it's power supply. SQL Server had a brief blackout until VM2 picked up where VM1 left. I then proceeded to turn Host1 back on. I could start all the VM's on Host1, except for the VM1 running the Cluster. Out of those 14 RDM's it is saying that 4 are unaccessible. For Host2 everything seems okay. The precise error message is "Virtual disk 'Hard disk 2' is a mapped direct-access LUN that is not accessible.Unable to access file sanfs://vmfs_uuid:xxx.....xxx/VM1/VM1_1.vmdk". All the disks reside in the same Datastore and the Datastore is functioning just fine.

1) I've tried to see if any mappings have changed but I've been unable to find anything wrong.
2) If I go to add a hard disk for VM1 on Host1, I see those four LUNs available for raw mapping, which is not supposed to happen.
3) I removed the four missing disks from VM1 and then imported them back using the same vmdk files and SCSI addresses as before. Everything is fine until I try to start the VM.
4) Clicking Manage Paths for those missing disks produce an error telling me that "There is no multipath configuration for this LUN.". This only happens on Host1, Host2 shows the MP configuration properly.

So, what should I do next? Even though this is a test environment and the SQL Server is serving clients as we speak (or write, whaeva), I'd like figure this out before we use this configuration for production use.

Thanks,

Mistah Will

P.S. first time poster, I hope I got it all right...