I'm trying to remove a drive. I have 18TB with 5TB free and trying to remove a 3TB drive. I just added a new 3TB drive, so theoretically it could just copy files to the new drive and be done. Removing appeared to do absolutely nothing, thought it seemed to work fine when I tested Drive Pool in my VM's. I found much better results by using the Drive Usage Limited plugin and disabling the drive I wanted to remove. After rebalancing, the drive is empty except for a couple GB. Drive Pool reports no unduplicated files on the drive, so I know I could just pull it and let it rebuild later.