Appendix B. Metadata Server daemon configuration Reference
Refer to this list of commands that can be used for the Metadata Server (MDS) daemon configuration.
- mon_force_standby_active
- Description
-
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. - Type
- Boolean
- Default
-
true
- max_mds
- Description
-
The number of active MDS daemons during cluster creation. Set under the
[mon]or[global]section in the Ceph configuration file. - Type
- 32-bit Integer
- Default
-
1
- mds_cache_memory_limit
- Description
-
The memory limit the MDS enforces for its cache. Red Hat recommends using this parameter instead of the
mds cache sizeparameter. - Type
- 64-bit Integer Unsigned
- Default
-
4294967296
- mds_cache_reservation
- Description
- 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.
- Type
- Float
- Default
-
0.05
- mds_cache_size
- Description
-
The number of inodes to cache. A value of 0 indicates an unlimited number. Red Hat recommends to use the
mds_cache_memory_limitto limit the amount of memory the MDS cache uses. - Type
- 32-bit Integer
- Default
-
0
- mds_cache_mid
- Description
- The insertion point for new items in the cache LRU, from the top.
- Type
- Float
- Default
-
0.7
- mds_dir_commit_ratio
- Description
- The fraction of directory that contains erroneous information before Ceph commits using a full update instead of partial update.
- Type
- Float
- Default
-
0.5
- mds_dir_max_commit_size
- Description
- The maximum size of a directory update in MB before Ceph breaks the directory into smaller transactions.
- Type
- 32-bit Integer
- Default
-
90
- mds_decay_halflife
- Description
- The half-life of the MDS cache temperature.
- Type
- Float
- Default
-
5
- mds_beacon_interval
- Description
- The frequency, in seconds, of beacon messages sent to the monitor.
- Type
- Float
- Default
-
4
- mds_beacon_grace
- Description
-
The interval without beacons before Ceph declares a MDS
laggyand possibly replaces it. - Type
- Float
- Default
-
15
- mds_blacklist_interval
- Description
- The blacklist duration for failed MDS daemons in the OSD map.
- Type
- Float
- Default
-
24.0*60.0
- mds_session_timeout
- Description
- The interval, in seconds, of client inactivity before Ceph times out capabilities and leases.
- Type
- Float
- Default
-
60
- mds_session_autoclose
- Description
-
The interval, in seconds, before Ceph closes a
laggyclient’s session. - Type
- Float
- Default
-
300
- mds_reconnect_timeout
- Description
- The interval, in seconds, to wait for clients to reconnect during a MDS restart.
- Type
- Float
- Default
-
45
- mds_tick_interval
- Description
- How frequently the MDS performs internal periodic tasks.
- Type
- Float
- Default
-
5
- mds_dirstat_min_interval
- Description
- The minimum interval, in seconds, to try to avoid propagating recursive statistics up the tree.
- Type
- Float
- Default
-
1
- mds_scatter_nudge_interval
- Description
- How quickly changes in directory statistics propagate up.
- Type
- Float
- Default
-
5
- mds_client_prealloc_inos
- Description
- The number of inode numbers to preallocate per client session.
- Type
- 32-bit Integer
- Default
-
1000
- mds_early_reply
- Description
- Determines whether the MDS allows clients to see request results before they commit to the journal.
- Type
- Boolean
- Default
-
true
- mds_use_tmap
- Description
-
Use
trivialmapfor directory updates. - Type
- Boolean
- Default
-
true
- mds_default_dir_hash
- Description
- The function to use for hashing files across directory fragments.
- Type
- 32-bit Integer
- Default
-
2,that is,rjenkins
- mds_log
- Description
-
Set to
trueif the MDS should journal metadata updates. Disable for benchmarking only. - Type
- Boolean
- Default
-
true
- mds_log_skip_corrupt_events
- Description
- Determines whether the MDS tries to skip corrupt journal events during journal replay.
- Type
- Boolean
- Default
-
false
- mds_log_max_events
- Description
-
The maximum events in the journal before Ceph initiates trimming. Set to
-1to disable limits. - Type
- 32-bit Integer
- Default
-
-1
- mds_log_max_segments
- Description
-
The maximum number of segments or objects in the journal before Ceph initiates trimming. Set to
-1to disable limits. - Type
- 32-bit Integer
- Default
-
30
- mds_log_max_expiring
- Description
- The maximum number of segments to expire in parallels.
- Type
- 32-bit Integer
- Default
-
20
- mds_log_eopen_size
- Description
-
The maximum number of inodes in an
EOpenevent. - Type
- 32-bit Integer
- Default
-
100
- mds_bal_sample_interval
- Description
- Determines how frequently to sample directory temperature when making fragmentation decisions.
- Type
- Float
- Default
-
3
- mds_bal_replicate_threshold
- Description
- The maximum temperature before Ceph attempts to replicate metadata to other nodes.
- Type
- Float
- Default
-
8000
- mds_bal_unreplicate_threshold
- Description
- The minimum temperature before Ceph stops replicating metadata to other nodes.
- Type
- Float
- Default
-
0
- mds_bal_frag
- Description
- Determines whether or not the MDS fragments directories.
- Type
- Boolean
- Default
-
false
- mds_bal_split_size
- Description
- 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.
- Type
- 32-bit Integer
- Default
-
10000
- mds_bal_split_rd
- Description
- The maximum directory read temperature before Ceph splits a directory fragment.
- Type
- Float
- Default
-
25000
- mds_bal_split_wr
- Description
- The maximum directory write temperature before Ceph splits a directory fragment.
- Type
- Float
- Default
-
10000
- mds_bal_split_bits
- Description
- The number of bits by which to split a directory fragment.
- Type
- 32-bit Integer
- Default
-
3
- mds_bal_merge_size
- Description
- The minimum directory size before Ceph tries to merge adjacent directory fragments.
- Type
- 32-bit Integer
- Default
-
50
- mds_bal_merge_rd
- Description
- The minimum read temperature before Ceph merges adjacent directory fragments.
- Type
- Float
- Default
-
1000
- mds_bal_merge_wr
- Description
- The minimum write temperature before Ceph merges adjacent directory fragments.
- Type
- Float
- Default
-
1000
- mds_bal_interval
- Description
- The frequency, in seconds, of workload exchanges between MDS nodes.
- Type
- 32-bit Integer
- Default
-
10
- mds_bal_fragment_interval
- Description
- The frequency, in seconds, of adjusting directory fragmentation.
- Type
- 32-bit Integer
- Default
-
5
- mds_bal_idle_threshold
- Description
- The minimum temperature before Ceph migrates a subtree back to its parent.
- Type
- Float
- Default
-
0
- mds_bal_max
- Description
- The number of iterations to run balancer before Ceph stops. For testing purposes only.
- Type
- 32-bit Integer
- Default
-
-1
- mds_bal_max_until
- Description
- The number of seconds to run balancer before Ceph stops. For testing purposes only.
- Type
- 32-bit Integer
- Default
-
-1
- mds_bal_mode
- Description
The method for calculating MDS load:
-
1= Hybrid. -
2= Request rate and latency. -
3= CPU load.
-
- Type
- 32-bit Integer
- Default
-
0
- mds_bal_min_rebalance
- Description
- The minimum subtree temperature before Ceph migrates.
- Type
- Float
- Default
-
0.1
- mds_bal_min_start
- Description
- The minimum subtree temperature before Ceph searches a subtree.
- Type
- Float
- Default
-
0.2
- mds_bal_need_min
- Description
- The minimum fraction of target subtree size to accept.
- Type
- Float
- Default
-
0.8
- mds_bal_need_max
- Description
- The maximum fraction of target subtree size to accept.
- Type
- Float
- Default
-
1.2
- mds_bal_midchunk
- Description
- Ceph migrates any subtree that is larger than this fraction of the target subtree size.
- Type
- Float
- Default
-
0.3
- mds_bal_minchunk
- Description
- Ceph ignores any subtree that is smaller than this fraction of the target subtree size.
- Type
- Float
- Default
-
0.001
- mds_bal_target_removal_min
- Description
- The minimum number of balancer iterations before Ceph removes an old MDS target from the MDS map.
- Type
- 32-bit Integer
- Default
-
5
- mds_bal_target_removal_max
- Description
- The maximum number of balancer iterations before Ceph removes an old MDS target from the MDS map.
- Type
- 32-bit Integer
- Default
-
10
- mds_replay_interval
- Description
-
The journal poll interval when in
standby-replaymode for ahot standby. - Type
- Float
- Default
-
1
- mds_shutdown_check
- Description
- The interval for polling the cache during MDS shutdown.
- Type
- 32-bit Integer
- Default
-
0
- mds_thrash_exports
- Description
- Ceph randomly exports subtrees between nodes. For testing purposes only.
- Type
- 32-bit Integer
- Default
-
0
- mds_thrash_fragments
- Description
- Ceph randomly fragments or merges directories.
- Type
- 32-bit Integer
- Default
-
0
- mds_dump_cache_on_map
- Description
- Ceph dumps the MDS cache contents to a file on each MDS map.
- Type
- Boolean
- Default
-
false
- mds_dump_cache_after_rejoin
- Description
- Ceph dumps MDS cache contents to a file after rejoining the cache during recovery.
- Type
- Boolean
- Default
-
false
- mds_verify_scatter
- Description
-
Ceph asserts that various scatter/gather invariants are
true. For developer use only. - Type
- Boolean
- Default
-
false
- mds_debug_scatterstat
- Description
-
Ceph asserts that various recursive statistics invariants are
true. For developer use only. - Type
- Boolean
- Default
-
false
- mds_debug_frag
- Description
- Ceph verifies directory fragmentation invariants when convenient. For developer use only.
- Type
- Boolean
- Default
-
false
- mds_debug_auth_pins
- Description
- The debug authentication pin invariants. For developer use only.
- Type
- Boolean
- Default
-
false
- mds_debug_subtrees
- Description
- Debugging subtree invariants. For developer use only.
- Type
- Boolean
- Default
-
false
- mds_kill_mdstable_at
- Description
- Ceph injects a MDS failure in a MDS Table code. For developer use only.
- Type
- 32-bit Integer
- Default
-
0
- mds_kill_export_at
- Description
- Ceph injects a MDS failure in the subtree export code. For developer use only.
- Type
- 32-bit Integer
- Default
-
0
- mds_kill_import_at
- Description
- Ceph injects a MDS failure in the subtree import code. For developer use only.
- Type
- 32-bit Integer
- Default
-
0
- mds_kill_link_at
- Description
- Ceph injects a MDS failure in a hard link code. For developer use only.
- Type
- 32-bit Integer
- Default
-
0
- mds_kill_rename_at
- Description
- Ceph injects a MDS failure in the rename code. For developer use only.
- Type
- 32-bit Integer
- Default
-
0
- mds_wipe_sessions
- Description
- Ceph deletes all client sessions on startup. For testing purposes only.
- Type
- Boolean
- Default
-
0
- mds_wipe_ino_prealloc
- Description
- Ceph deletes inode preallocation metadata on startup. For testing purposes only.
- Type
- Boolean
- Default
-
0
- mds_skip_ino
- Description
- The number of inode numbers to skip on startup. For testing purposes only.
- Type
- 32-bit Integer
- Default
-
0
- mds_standby_for_name
- Description
- The MDS daemon is a standby for another MDS daemon of the name specified in this setting.
- Type
- String
- Default
- N/A
- mds_standby_for_rank
- Description
- An instance of the MDS daemon is a standby for another MDS daemon instance of this rank.
- Type
- 32-bit Integer
- Default
-
-1
- mds_standby_replay
- Description
-
Determines whether the MDS daemon polls and replays the log of an active MDS when used as a
hot standby. - Type
- Boolean
- Default
-
false
