I took a clone backup for windows failover cluster system from vmware system which used raw disks. Raw disks automatically converted to vmdk disk via vmware. I restored this clone backup as new standalone server. I started system but my disks were reserved status and I could not use these. I implemented below steps to convert disk status from reserved to online.

Error

How to Change Disk Status From Reserved to Online on Windows_RDM to VMDK

Solution

Delete Reserved Disks Information From Regedit

You have to delete content from AttachedDisks parameter. You have to restart server after delete operation.

How to Change Disk Status From Reserved to Online on Windows_RDM to VMDK_02

Set SAN Policy to Online

If SAN Policy is OfflineAll, you have to set this parameter to OnlineAll

How to Change Disk Status From Reserved to Online on Windows_RDM to VMDK_03

Disks Make Online

How to Change Disk Status From Reserved to Online on Windows_RDM to VMDK_04

Change Read Only Status to Read Write

How to Change Disk Status From Reserved to Online on Windows_RDM to VMDK_05

Finally, you can use disks.

http://www.fatihacar.com/blog/how-to-change-disk-status-from-reserved-to-online-on-windows/