When restoring the OS of the cluster servers, sometime the cluster disk will becomes reserved / RAW.

Do the following to release the cluster reservation.

  1. Install the cluster feature

  2. find the disk number on the disk manager

  3. Run powershell with administrator right, clear-clusterdiskreservation -disk 2

  4. Remove the cluster feature when finish

or

CHKDSK O: /F /R (/X)