a temporary placement group acting set that is used while backfilling the
primary OSD. Assume that the acting set is ``[0,1,2]`` and we are
``active+clean``. Now assume that something happens and the acting set
- becomes ``[2,1,2]``. Under these circumstances, OSD ``3`` is empty and can't
+ becomes ``[3,1,2]``. Under these circumstances, OSD ``3`` is empty and can't
serve reads even though it is the primary. ``osd.3`` will respond by
requesting a *PG temp* of ``[1,2,3]`` to the monitors using a ``MOSDPGTemp``
message, and ``osd.1`` will become the primary temporarily. ``osd.1`` will