ceph/doc/rados/configuration/pool-pg-config-ref.rst

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Pool, PG and CRUSH Config Reference
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.. 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``
``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 pool default crush replicated ruleset``
:Description: The default CRUSH ruleset to use when creating a replicated pool.
:Type: 8-bit Integer
:Default: ``0``
``osd pool erasure code stripe width``
:Description: Sets the desired size, in bytes, of an object stripe on every
erasure coded pools. Every object if size S will be stored as
N stripes and each stripe will be encoded/decoded individually.
: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``
.. _pool: ../../operations/pools
.. _Monitoring OSDs and PGs: ../../operations/monitoring-osd-pg#peering