ESX Server mounts the storage using UUID. With the hard disk changed, UUID changes too. Hence, ESX fails to mount
ESX Server mounts the storage using Universally Unique Identifier (UUID). With the hard disk changed, UUID changes too. As a result ESX Server fails to recognize the restored hard disk and mount the storage. Hence, Guest Operating Systems fail to boot.
To migrate ESX Server to new hard disks you need to do the following:
esxcfg-advcfg -g /LVM/EnableResignature
There will be either 1 or 0 value output. If the value is 0, then ESX will not automatically update the VMFS header with new LUN and UUID. Therefore this value should be set to 1:
esxcfg-advcfg -s 1 /LVM/EnableResignature
shutdown -r 0
(!) The Guest Operating Systems will remain in the unknown state. So, you should reinitialize guest virtual machines:
After this the ESX Server should work properly and Guest Operating Systems should boot.