Ceph » RADOS

ceph version:13.2.1
kernel client 4.17
I created the cache data pool as ceph's instructions:
(1) ceph osd tier add cold-pool hot-pool
(2) ceph osd tier cache-mode hot-pool readonly
(3) ceph osd tier set-overlay cold hot
(4) config other tier cache param

step 1: the vim will be hanged when I save a changed file.(this bug has been reported by me.)
step 2: for step 1's reason, I ran the command that ceph osd tier cache-mode hot-pool none,but not ran the next three commands: (1)rados -p hot-pool cache-flush-evict-all (2) ceph osd tier remove-overlay cold-pool (3)ceph osd tier remove cold hot.
problem 1:
In this situtation, I just changed the cahce mode to none,but not removed overlay;When I touch a file and sync the data to data pool,I found that the file's object was stored in cache pool and not in data pool.