``hdd`` or ``ssd`` or ``nvme``), allowing them to be conveniently targeted by
CRUSH rules. This is especially useful when mixing device types within hosts.
+.. _crush_map_default_types:
+
Types and Buckets
-----------------
* For large clusters, some small percentages of PGs map to fewer than
the desired number of OSDs. This is more prevalent when there are
- mutiple hierarchy layers in use (e.g., ``row``, ``rack``, ``host``, ``osd``).
+ multiple hierarchy layers in use (e.g., ``row``, ``rack``, ``host``, ``osd``).
* When some OSDs are marked out, the data tends to get redistributed
to nearby OSDs instead of across the entire hierarchy.