This was surprisingly tricking issue to deal with. If you are copying TO or FROM a Deduplicated file share you must make certain:
- Do NOT robocopy the a partition or volume – only robocopy shares\folders. This is because the dedup information is stored in the SYSTEM VOLUME INFORMATION folder and at folder can not be migrated with robocopy. It needs to be built on the partition\volume that the dedup exists on.
- Make sure you do NOT use /XJ switch. XJ is Exclude Junction points and junction points (JP’s) are tied into the deduplication process. In previous versions of Windows, starting with Vista, I have needed to use /XJ because if robocopy hit tried to copy a JP’s the destination disk would fill up with thousands of nested folders matching the name of the JP. Worse this problem was not readily recoverable by deleting those folders, even using the old POSIX commands. The only solution, according to Microsoft Partner Support (and from my experience) was to reformat the disk… not cool.
Microsoft Partner Support also indicated that you should use the /ZB (backup mode) switch but our experience thus far has not borne this out as a requirement.