Bug in removal of data DeDuplication

Copper Contributor

Hello All,


in the release version of Windows 2019 17764.194 with latest update there is a bug when you remove data deduplication.


- A drive which was either 1) undeduped using a powershell command like "start-dedupjob -Volume X: -Type Unoptimization" or 2) was not undeduped but just formatted after the Deduplicated service was turned off and the server rebooted .. in either case, no matter if the drive is a SATA SSD or a USB external drive, these drives cannot enable folder compression anymore >> "Compress contents to save disk space".


Even you you remove the partition in the Disk Mangement interface, and reformat, the drives have that compression setting disabled, means you cannot click the little checkbox to enable drive compression anymore.


What seems to be the issue is that drives which before were used for DeDuplication are permanently marked and blocked by Windows to enable folder compression.


I would expect that after removal of the DeDupe services of a drive that folder compression should be available again.


Best Regards,



1 Reply

It is possible that the NTFS cluster size after the re-format is >4KB thus folder compression is disabled. Could you please confirm the cluster size?