@etorix In part you are right. The pool that never had anything cloned at or after the time of device removal is not affected. The problem is in “after”. As I repeated many times in my criticism of device removal, one of its design flaws is that once started it might never actually finish, continuing to remap block pointers forever as long as something modifies indirect blocks or dnodes. And it is the remapping process that is incompatible with block cloning. My incoming patch is going to disable remapping for cloned blocks, same as already done for deduped and ganged ones for similar reasons. So if as in @winnielinnie case he never had anything cloned, then disabling it will keep him safe (but updating would do it too). If there are or were some cloned blocks since device removal, then pool might already be toast and disabling further clones may only slightly reduce the issue.