A physical Windows 2008 R2 Server is converted to a virtual machine using VMware vCenter Converter. Upon completion of the conversion and subsequent power on operation, the virtual machine fails to…

If the wrong SCSI controller type (for example, LSI Logic instead of BusLogic, or vice versa) is selected during conversion, Windows will not have the matching driver loaded at boot time, preventing it from accessing the virtual disk and causing the INACCESSIBLE_BOOT_DEVICE stop error.

Physical machine storage drivers (such as a vendor-specific RAID or HBA driver) migrated into the virtual machine from the source are incompatible with the virtual hardware, and if Windows attempts to use them instead of the correct virtual SCSI driver, the boot device becomes inaccessible.

Thick provisioning is a disk space allocation method and does not affect how Windows detects or accesses the boot device; a thick-provisioned VMDK is functionally identical to a thin-provisioned one from the guest OS perspective.

Taking a snapshot after conversion creates a point-in-time state record but does not alter the virtual machine's disk or driver configuration, so it cannot cause a boot device to become inaccessible.