Minor correction: you can disable it, but this doesn't change the status of the data already deduped. This is in fact true also when you enable it: current data

Minor correction: you can disable it, but this doesn't change the status of the data already deduped. This is in fact true also when you enable it: current data is unaffected by the change, you need to move/copy it. The biggest issue is that there is no official tool to have a list of files that are currently deduped (I had to write a script that parse the output of zdb) so if you're not sure you have to move all the data out of the dataset.