_forgetDelete error

Question: What does this message mean?

10.1.1.151 <179>2015-03-05 23:10:33,902 DISK.ZFS ERROR: [/dev/sdb] _forgetDelete: uuid(61d36709f5afbaf4a76f441815908582) of forgotten delete otherwise indexed!

Answer: It means that a delete got journaled, but somehow the stream didn't get deleted. You should info the stream to see if it still exists in the cluster.