This warning meaning that the node could not recognize the used space, due to lack of information in the database, it should be updated during filewalker, which starts after the node restart.
This error:
You need to check the reason of inability to delete a piece, perhaps related to files permissions.
This error
means that your disk subsystem is slow, the one time occurrence should not be a problem, it will retry, but if you see a lot of such errors, it’s advisable to move databases to SSD: How to move DB’s to SSD on Docker