Appendix B. Metadata Server daemon configuration Reference

mon_force_standby_active

If set to true, monitors force MDS in standby replay mode to be active.

Set under the [mon] or [global] section in the Ceph configuration file.

Boolean

true

max_mds

The number of active MDS daemons during cluster creation.

Set under the [mon] or [global] section in the Ceph configuration file.

32-bit Integer

1

mds_cache_memory_limit

The memory limit the MDS enforces for its cache.

Red Hat recommends using this parameter instead of the mds cache size parameter.

64-bit Integer Unsigned

4294967296

mds_cache_reservation

The cache reservation, memory or inodes, for the MDS cache to maintain.

The value is a percentage of the maximum cache configured.

Once the MDS begins dipping into its reservation, it recalls client state until its cache size shrinks to restore the reservation.

Float

0.05

mds_cache_size

The number of inodes to cache. A value of 0 indicates an unlimited number.

Red Hat recommends to use the mds_cache_memory_limit to limit the amount of memory the MDS cache uses.

32-bit Integer

0

mds_cache_mid

The insertion point for new items in the cache LRU, from the top.

Float

0.7

mds_dir_commit_ratio

The fraction of directory that contains erroneous information before Ceph commits using a full update instead of partial update.

Float

0.5

mds_dir_max_commit_size

The maximum size of a directory update in MB before Ceph breaks the directory into smaller transactions.

32-bit Integer

10

mds_decay_halflife

The half-life of the MDS cache temperature.

Float

5

mds_beacon_interval

The frequency, in seconds, of beacon messages sent to the monitor.

Float

4

mds_beacon_grace

The interval without beacons before Ceph declares a MDS laggy and possibly replaces it.

Float

15

mds_blacklist_interval

The blacklist duration for failed MDS daemons in the OSD map.

Float

24.0*60.0

mds_session_timeout

The interval, in seconds, of client inactivity before Ceph times out capabilities and leases.

Float

60

mds_session_autoclose

The interval, in seconds, before Ceph closes a laggy client’s session.

Float

300

mds_reconnect_timeout

The interval, in seconds, to wait for clients to reconnect during a MDS restart.

Float

45

mds_tick_interval

How frequently the MDS performs internal periodic tasks.

Float

5

mds_dirstat_min_interval

The minimum interval, in seconds, to try to avoid propagating recursive statistics up the tree.

Float

1

mds_scatter_nudge_interval

How quickly changes in directory statistics propagate up.

Float

5

mds_client_prealloc_inos

The number of inode numbers to preallocate per client session.

32-bit Integer

1000

mds_early_reply

Determines whether the MDS allows clients to see request results before they commit to the journal.

Boolean

true

mds_use_tmap

Use trivialmap for directory updates.

Boolean

true

mds_default_dir_hash

The function to use for hashing files across directory fragments.

32-bit Integer

2, that is, rjenkins

mds_log

Set to true if the MDS should journal metadata updates. Disable for benchmarking only.

Boolean

true

mds_log_skip_corrupt_events

Determines whether the MDS tries to skip corrupt journal events during journal replay.

Boolean

false

mds_log_max_events

The maximum events in the journal before Ceph initiates trimming.

Set to -1 to disable limits.

32-bit Integer

-1

mds_log_max_segments

The maximum number of segments or objects in the journal before Ceph initiates trimming.

Set to -1 to disable limits.

32-bit Integer

30

mds_log_max_expiring

The maximum number of segments to expire in parallels.

32-bit Integer

20

mds_log_eopen_size

The maximum number of inodes in an EOpen event.

32-bit Integer

100

mds_bal_sample_interval

Determines how frequently to sample directory temperature when making fragmentation decisions.

Float

3

mds_bal_replicate_threshold

The maximum temperature before Ceph attempts to replicate metadata to other nodes.

Float

8000

mds_bal_unreplicate_threshold

The minimum temperature before Ceph stops replicating metadata to other nodes.

Float

0

mds_bal_frag

Determines whether or not the MDS fragments directories.

Boolean

false

mds_bal_split_size

The maximum directory size before the MDS splits a directory fragment into smaller bits.

The root directory has a default fragment size limit of 10000.

32-bit Integer

10000

mds_bal_split_rd

The maximum directory read temperature before Ceph splits a directory fragment.

Float

25000

mds_bal_split_wr

The maximum directory write temperature before Ceph splits a directory fragment.

Float

10000

mds_bal_split_bits

The number of bits by which to split a directory fragment.

32-bit Integer

3

mds_bal_merge_size

The minimum directory size before Ceph tries to merge adjacent directory fragments.

32-bit Integer

50

mds_bal_merge_rd

The minimum read temperature before Ceph merges adjacent directory fragments.

Float

1000

mds_bal_merge_wr

The minimum write temperature before Ceph merges adjacent directory fragments.

Float

1000

mds_bal_interval

The frequency, in seconds, of workload exchanges between MDS nodes.

32-bit Integer

10

mds_bal_fragment_interval

The frequency, in seconds, of adjusting directory fragmentation.

32-bit Integer

5

mds_bal_idle_threshold

The minimum temperature before Ceph migrates a subtree back to its parent.

Float

0

mds_bal_max

The number of iterations to run balancer before Ceph stops.

For testing purposes only.

32-bit Integer

-1

mds_bal_max_until

The number of seconds to run balancer before Ceph stops.

For testing purposes only.

32-bit Integer

-1

mds_bal_mode

The method for calculating MDS load: * 1 = Hybrid * 2 = Request rate and latency * 3 = CPU load

32-bit Integer

0

mds_bal_min_rebalance

The minimum subtree temperature before Ceph migrates.

Float

0.1

mds_bal_min_start

The minimum subtree temperature before Ceph searches a subtree.

Float

0.2

mds_bal_need_min

The minimum fraction of target subtree size to accept.

Float

0.8

mds_bal_need_max

The maximum fraction of target subtree size to accept.

Float

1.2

mds_bal_midchunk

Ceph migrates any subtree that is larger than this fraction of the target subtree size.

Float

0.3

mds_bal_minchunk

Ceph ignores any subtree that is smaller than this fraction of the target subtree size.

Float

0.001

mds_bal_target_removal_min

The minimum number of balancer iterations before Ceph removes an old MDS target from the MDS map.

32-bit Integer

5

mds_bal_target_removal_max

The maximum number of balancer iterations before Ceph removes an old MDS target from the MDS map.

32-bit Integer

10

mds_replay_interval

The journal poll interval when in standby-replay mode for a hot standby.

Float

1

mds_shutdown_check

The interval for polling the cache during MDS shutdown.

32-bit Integer

0

mds_thrash_exports

Ceph randomly exports subtrees between nodes.

For testing purposes only.

32-bit Integer

0

mds_thrash_fragments

Ceph randomly fragments or merges directories.

32-bit Integer

0

mds_dump_cache_on_map

Ceph dumps the MDS cache contents to a file on each MDS map.

Boolean

false

mds_dump_cache_after_rejoin

Ceph dumps MDS cache contents to a file after rejoining the cache during recovery.

Boolean

false

mds_verify_scatter

Ceph asserts that various scatter/gather invariants are true.

For developer use only.

Boolean

false

mds_debug_scatterstat

Ceph asserts that various recursive statistics invariants are true.

For developer use only.

Boolean

false

mds_debug_frag

Ceph verifies directory fragmentation invariants when convenient.

For developer use only.

Boolean

false

mds_debug_auth_pins

The debug authentication pin invariants.

For developer use only.

Boolean

false

mds_debug_subtrees

Debugging subtree invariants.

For developer use only.

Boolean

false

mds_kill_mdstable_at

Ceph injects a MDS failure in a MDS Table code.

For developer use only.

32-bit Integer

0

mds_kill_export_at

Ceph injects a MDS failure in the subtree export code.

For developer use only.

32-bit Integer

0

mds_kill_import_at

Ceph injects a MDS failure in the subtree import code.

For developer use only.

32-bit Integer

0

mds_kill_link_at

Ceph injects a MDS failure in a hard link code.

For developer use only.

32-bit Integer

0

mds_kill_rename_at

Ceph injects a MDS failure in the rename code.

For developer use only.

32-bit Integer

0

mds_wipe_sessions

Ceph deletes all client sessions on startup.

For testing purposes only.

Boolean

0

mds_wipe_ino_prealloc

Ceph deletes inode preallocation metadata on startup.

For testing purposes only.

Boolean

0

mds_skip_ino

The number of inode numbers to skip on startup.

For testing purposes only.

32-bit Integer

0

mds_standby_for_name

The MDS daemon is a standby for another MDS daemon of the name specified in this setting.

String

N/A

mds_standby_for_rank

An instance of the MDS daemon is a standby for another MDS daemon instance of this rank.

32-bit Integer

-1

mds_standby_replay

Determines whether the MDS daemon polls and replays the log of an active MDS when used as a hot standby.

Boolean

false