VMware ESX/ESXi Update 4 (U4) has brought good and bad news for all of you HP Proliant ML110 G5 owners out there. Update 4 as well and providing plenty of really good bug fixes has also increased ESX’s hardware compatibility list to resolve an issue with some host CD/DVD drives being used from a VM.  Now falling into this hardware compatibility list is the Intel ICH-9 SATA controllers – which just happens to be used in the ML110 G5.

“This is great news!” I hear you say, and it is, though this newly found ‘official’ compatibility will potentially give you a little grief when upgrading your ESX/ESXi host to U4 and you get the following message (“The VMware ESX Server does not have persistent storage") that informs you that your previous VMFS data store is no longer present:

No need to press the panic button quite yet.  The reason for this, after upgrading your ESX host to Update 4 (U4) on your HP ML110, is that ESX will now see the onboard RAID controller as an IDE device and no longer SATA.

Now rather than me re-invent the wheel and provide step by step instructions on how to resolve this issue so that your local VMFS storage is once again detected and presented to the ESX host here is a good article by Dave Mishchenko that clearly outlines these steps.

After following these steps your ML110 G5 should once again see your local VMFS storage once more and all will be happy with world.