Appendix E. Pools, placement groups, and CRUSH configuration options

mon_allow_pool_delete

Allows a monitor to delete a pool. In RHCS 3 and later releases, the monitor cannot delete the pool by default as an added measure to protect data.

Boolean

false

mon_max_pool_pg_num

The maximum number of placement groups per pool.

Integer

65536

mon_pg_create_interval

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

Float

30.0

mon_pg_stuck_threshold

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

32-bit Integer

300

mon_pg_min_inactive

Ceph issues a HEALTH_ERR status in the cluster log if the number of PGs that remain inactive longer than the mon_pg_stuck_threshold exceeds this setting. The default setting is one PG. A non-positive number disables this setting.

Integer

1

mon_pg_warn_max_per_osd

Ceph issues a HEALTH_WARN status in the cluster log if the average number of PGs per OSD in the cluster is greater than this setting. A non-positive number disables this setting.

Integer

300

mon_pg_warn_min_per_osd

Ceph issues a HEALTH_WARN status in the cluster log if the average number of PGs per OSD in the cluster is less than this setting. A non-positive number disables this setting.

Integer

30

mon_pg_warn_min_objects

Do not warn if the total number of objects in the cluster is below this number.

Integer

1000

mon_pg_warn_min_pool_objects

Do not warn on pools whose object number is below this number.

Integer

1000

mon_pg_check_down_all_threshold

The threshold of down OSDs by percentage after which Ceph checks all PGs to ensure they are not stuck or stale.

Float

0.5

mon_pg_warn_max_object_skew

Ceph issue a HEALTH_WARN status in the cluster log if the average number of objects in a pool is greater than mon pg warn max object skew times the average number of objects for all pools. A non-positive number disables this setting.

Float

10

mon_delta_reset_interval

The number of seconds of inactivity before Ceph resets the PG delta to zero. Ceph keeps track of the delta of the used space for each pool to aid administrators in evaluating the progress of recovery and performance.

Integer

10

mon_osd_max_op_age

The maximum age in seconds for an operation to complete before issuing a HEALTH_WARN status.

Float

32.0

osd_pg_bits

Placement group bits per Ceph OSD Daemon.

32-bit Integer

6

osd_pgp_bits

The number of bits per Ceph OSD Daemon for Placement Groups for Placement purpose (PGPs).

32-bit Integer

6

osd_crush_chooseleaf_type

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

32-bit Integer

1. Typically a host containing one or more Ceph OSD Daemons.

osd_pool_default_crush_replicated_ruleset

The default CRUSH ruleset to use when creating a replicated pool.

8-bit Integer

0

osd_pool_erasure_code_stripe_unit

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 be overridden by the stripe_unit setting in an erasure code profile.

Unsigned 32-bit Integer

4096

osd_pool_default_size

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}.

32-bit Integer

3

osd_pool_default_min_size

Sets the minimum number of written replicas for objects in the pool in order to acknowledge a write operation to the client. If the 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.

32-bit Integer

0, which means no particular minimum. If 0, minimum is size - (size / 2).

osd_pool_default_pg_num

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

32-bit Integer

32

osd_pool_default_pgp_num

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.

32-bit Integer

0

osd_pool_default_flags

The default flags for new pools.

32-bit Integer

0

osd_max_pgls

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

Unsigned 64-bit Integer

1024

osd_min_pg_log_entries

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

32-bit Int Unsigned

250

osd_default_data_pool_replay_window

The time, in seconds, for an OSD to wait for a client to replay a request.

32-bit Integer

45