This document will explain you the steps involved in working with encrypted hard disks.
ManageEngine OS Deployer 5 generally recommends disabling any hard disk encryption during image capturing and deploying the image to hard disks. Example of few disk level encryption applications would be Bitlocker , Mcafee Endpoint protection etc.
If image capturing is done on such encrypted disk , then sector by sector image capturing will be done. This means OS Deployer will capture all the parts of the disk including empty sectors and bad sectors. This process will take comparatively longer time when compared to image capturing of non encrypted disks where only the data parts will be captured and also can be compressed.Consequently the captured image will be of the same size as the disk itself.
When deploying image to encrypted disks , we generally observe failed executions most of the time and hence it is recommended to ensure the target disk is clean of any encryption.