Ceph: 缓存层统计信息

关于如何从缓存池中检索缓存统计信息的快速提示。

只需使用 admin socket

```bash $ sudo ceph daemon osd.{id} perf dump ...

 "tier_promote": 1425,
 "tier_flush": 0,
 "tier_flush_fail": 0,
 "tier_try_flush": 216,
 "tier_try_flush_fail": 21,
 "tier_evict": 1413,
 "tier_whiteout": 201,
 "tier_dirty": 671,
 "tier_clean": 216,
 "tier_delay": 16,

... ```