======================================
 Pool, PG and CRUSH Config Reference
======================================

.. index:: pools; configuration

When you create pools and set the number of placement groups for the pool, Ceph
uses default values when you don't specifically override the defaults. **We
recommend** overridding some of the defaults. Specifically, we recommend setting
a pool's replica size and overriding the default number of placement groups. You
can specifically set these values when running `pool`_ commands. You can also
override the defaults by adding new ones in the ``[global]`` section of  your
Ceph configuration file. 


.. literalinclude:: pool-pg.conf
   :language: ini



``mon max pool pg num``

:Description: The maximum number of placement groups per pool.
:Type: Integer
:Default: ``65536``


``mon pg create interval`` 

:Description: Number of seconds between PG creation in the same 
              Ceph OSD Daemon.

:Type: Float
:Default: ``30.0``


``mon pg stuck threshold`` 

:Description: Number of seconds after which PGs can be considered as 
              being stuck.

:Type: 32-bit Integer
:Default: ``300``

``mon pg min inactive``

:Description: Issue a ``HEALTH_ERR`` in cluster log if the number of PGs stay
              inactive longer than ``mon_pg_stuck_threshold`` exceeds this
              setting. A non-positive number means disabled, never go into ERR.
:Type: Integer
:Default: ``1``


``mon pg warn min per osd``

:Description: Issue a ``HEALTH_WARN`` in cluster log if the average number
              of PGs per (in) OSD is under this number. (a non-positive number
              disables this)
:Type: Integer
:Default: ``30``


``mon pg warn max per osd``

:Description: Issue a ``HEALTH_WARN`` in cluster log if the average number
              of PGs per (in) OSD is above this number. (a non-positive number
              disables this)
:Type: Integer
:Default: ``300``


``mon pg warn min objects``

:Description: Do not warn if the total number of objects in cluster is below
              this number
:Type: Integer
:Default: ``1000``


``mon pg warn min pool objects``

:Description: Do not warn on pools whose object number is below this number
:Type: Integer
:Default: ``1000``


``mon pg check down all threshold``

:Description: Threshold of down OSDs percentage after which we check all PGs
              for stale ones.
:Type: Float
:Default: ``0.5``


``mon pg warn max object skew``

:Description: Issue a ``HEALTH_WARN`` in cluster log if the average object number
              of a certain pool is greater than ``mon pg warn max object skew`` times
              the average object number of the whole pool. (a non-positive number
              disables this)
:Type: Float
:Default: ``10``


``mon delta reset interval``

:Description: Seconds of inactivity before we reset the pg delta to 0. We keep
              track of the delta of the used space of each pool, so, for
              example, it would be easier for us to understand the progress of
              recovery or the performance of cache tier. But if there's no
              activity reported for a certain pool, we just reset the history of
              deltas of that pool.
:Type: Integer
:Default: ``10``


``mon osd max op age``

:Description: Maximum op age before we get concerned (make it a power of 2).
              A ``HEALTH_WARN`` will be issued if a request has been blocked longer
              than this limit.
:Type: Float
:Default: ``32.0``


``osd pg bits``

:Description: Placement group bits per Ceph OSD Daemon.
:Type: 32-bit Integer
:Default: ``6`` 


``osd pgp bits``

:Description: The number of bits per Ceph OSD Daemon for PGPs.
:Type: 32-bit Integer
:Default: ``6``


``osd crush chooseleaf type``

:Description: The bucket type to use for ``chooseleaf`` in a CRUSH rule. Uses 
              ordinal rank rather than name.

:Type: 32-bit Integer
:Default: ``1``. Typically a host containing one or more Ceph OSD Daemons.


``osd crush initial weight``

:Description: The initial crush weight for newly added osds into crushmap.

:Type: Double
:Default: ``the size of newly added osd in TB``. By default, the initial crush
          weight for the newly added osd is set to its volume size in TB.
          See `Weighting Bucket Items`_ for details.


``osd pool default crush rule``

:Description: The default CRUSH rule to use when creating a replicated pool.
:Type: 8-bit Integer
:Default: ``-1``, which means "pick the rule with the lowest numerical ID and 
          use that".  This is to make pool creation work in the absence of rule 0.


``osd pool erasure code stripe unit``

:Description: Sets the default size, in bytes, of a chunk of an object
              stripe for erasure coded pools. Every object of size S
              will be stored as N stripes, with each data chunk
              receiving ``stripe unit`` bytes. Each stripe of ``N *
              stripe unit`` bytes will be encoded/decoded
              individually. This option can is overridden by the
              ``stripe_unit`` setting in an erasure code profile.

:Type: Unsigned 32-bit Integer
:Default: ``4096``


``osd pool default size``

:Description: Sets the number of replicas for objects in the pool. The default
              value is the same as
              ``ceph osd pool set {pool-name} size {size}``.

:Type: 32-bit Integer
:Default: ``3``


``osd pool default min size``

:Description: Sets the minimum number of written replicas for objects in the 
             pool in order to acknowledge a write operation to the client. 
             If minimum is not met, Ceph will not acknowledge the write to the 
             client. This setting ensures a minimum number of replicas when 
             operating in ``degraded`` mode.

:Type: 32-bit Integer
:Default: ``0``, which means no particular minimum. If ``0``, 
          minimum is ``size - (size / 2)``.


``osd pool default pg num`` 

:Description: The default number of placement groups for a pool. The default 
              value is the same as ``pg_num`` with ``mkpool``.

:Type: 32-bit Integer
:Default: ``8`` 


``osd pool default pgp num`` 

:Description: The default number of placement groups for placement for a pool. 
              The default value is the same as ``pgp_num`` with ``mkpool``. 
              PG and PGP should be equal (for now).

:Type: 32-bit Integer
:Default: ``8``


``osd pool default flags``

:Description: The default flags for new pools. 
:Type: 32-bit Integer
:Default: ``0``


``osd max pgls``

:Description: The maximum number of placement groups to list. A client 
              requesting a large number can tie up the Ceph OSD Daemon.

:Type: Unsigned 64-bit Integer
:Default: ``1024``
:Note: Default should be fine.


``osd min pg log entries`` 

:Description: The minimum number of placement group logs to maintain 
              when trimming log files.

:Type: 32-bit Int Unsigned
:Default: ``1000``


``osd default data pool replay window``

:Description: The time (in seconds) for an OSD to wait for a client to replay
              a request.

:Type: 32-bit Integer
:Default: ``45``

``osd max pg per osd hard ratio``

:Description: The ratio of number of PGs per OSD allowed by the cluster before
              OSD refuses to create new PGs. OSD stops creating new PGs if the number
              of PGs it serves exceeds
              ``osd max pg per osd hard ratio`` \* ``mon max pg per osd``.

:Type: Float
:Default: ``2``

.. _pool: ../../operations/pools
.. _Monitoring OSDs and PGs: ../../operations/monitoring-osd-pg#peering
.. _Weighting Bucket Items: ../../operations/crush-map#weightingbucketitems
