>= 12.2.0
---------

- *CephFS*:

  * Limiting MDS cache via a memory limit is now supported using the new
    mds_cache_memory_limit config option (1GB by default).  A cache reservation
    can also be specified using mds_cache_reservation as a percentage of the
    limit (5% by default). Limits by inode count are still supported using
    mds_cache_size. Setting mds_cache_size to 0 (the default) disables the
    inode limit.

* The maximum number of PGs per OSD before the monitor issues a
  warning has been reduced from 300 to 200 PGs.  200 is still twice
  the generally recommended target of 100 PGs per OSD.  This limit can
  be adjusted via the ``mon_pg_warn_max_per_osd`` option on the
  monitors.

* Creating pools or adjusting pg_num will now fail if the change would
  make the number of PGs per OSD exceed the configured
  ``mon_pg_warn_max_per_osd`` limit.  The option can be adjusted if it
  is really necessary to create a pool with more PGs.