I know this is an older thread but wanted to add something. I am a newish unRaid user and made the mistake of dumping every drive I had lying around (yes, I know now that it was stupid) including 3 tiny 320GB drives. These drives are old and haven't been written to yet. I want to pull them and drop in a 5TB drive. At the same time I want to add more SSDs to my cache pool. Now I could just leave them all in but it will push me past my 12 drive limit and I don't want to go to a pro license. I for one, would think a simple button solution would be great!