path: root/doc/cephfs/mds-config-ref.rst

======================
 MDS Config Reference
======================

``mds_cache_memory_limit``

:Description: The memory limit the MDS should enforce for its cache.
:Type:  64-bit Integer Unsigned
:Default: ``4G``

``mds_cache_reservation``

:Description: The cache reservation (memory or inodes) for the MDS cache to maintain.
              Once the MDS begins dipping into its reservation, it will recall
              client state until its cache size shrinks to restore the
              reservation.
:Type:  Float
:Default: ``0.05``


``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 is dirty 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 before Ceph breaks it into 
              smaller transactions (MB).
              
:Type:  32-bit Integer
:Default: ``10``

``mds_dir_max_entries``

:Description: The maximum number of entries before any new entries are rejected
              with ENOSPC.
:Type:  64-bit Integer Unsigned
:Default: ``0``

``mds_decay_halflife``

:Description: The half-life of 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 an MDS laggy 
              (and possibly replace it).
              
:Type:  Float
:Default: ``15``


``mds_blocklist_interval``

:Description: The blocklist duration for failed MDSs in the OSD map. Note,
              this controls how long failed MDS daemons will stay in the
              OSDMap blocklist. It has no effect on how long something is
              blocklisted when the administrator blocklists it manually. For
              example, ``ceph osd blocklist add`` will still use the default
              blocklist time.
:Type:  Float
:Default: ``24.0*60.0``


``mds_reconnect_timeout``

:Description: The interval (in seconds) to wait for clients to reconnect 
              during 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 stats up the tree.
              
:Type:  Float
:Default: ``1``

``mds_scatter_nudge_interval``

:Description: How quickly dirstat changes 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 should allow clients to see request 
              results before they commit to the journal.

: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`` (i.e., rjenkins)


``mds_log_skip_corrupt_events``

:Description: Determines whether the MDS should try to skip corrupt journal 
              events during journal replay.
              
:Type:  Boolean
:Default:  ``false``


``mds_log_max_events``

:Description: The maximum events in the journal before we initiate trimming.
              Set to ``-1`` to disable limits.
              
:Type:  32-bit Integer
:Default: ``-1``


``mds_log_max_segments``

:Description: The maximum number of segments (objects) in the journal before 
              we initiate trimming. Set to ``-1`` to disable limits.

:Type:  32-bit Integer
:Default: ``128``


``mds_bal_sample_interval``

:Description: Determines how frequently to sample directory temperature 
              (for 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_split_size``

:Description: The maximum directory size before the MDS will split a directory 
              fragment into smaller bits.
              
: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_interval``

:Description: The frequency (in seconds) of workload exchanges between MDSs.
:Type:  32-bit Integer
:Default: ``10``


``mds_bal_fragment_interval``

:Description: The delay (in seconds) between a fragment being eligible for split
              or merge and executing the fragmentation change.
:Type:  32-bit Integer
:Default: ``5``


``mds_bal_fragment_fast_factor``

:Description: The ratio by which frags may exceed the split size before
              a split is executed immediately (skipping the fragment interval)
:Type:  Float
:Default: ``1.5``

``mds_bal_fragment_size_max``

:Description: The maximum size of a fragment before any new entries
              are rejected with ENOSPC.
:Type:  32-bit Integer
:Default: ``100000``

``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. 
              (used 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. 
              (used for testing purposes only)

:Type:  32-bit Integer
:Default: ``-1``


``mds_bal_mode``

:Description: The method for calculating MDS load. 

              - ``0`` = Hybrid.
              - ``1`` = Request rate and latency. 
              - ``2`` = 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 will migrate any subtree that is larger than this fraction 
              of the target subtree size.
              
:Type:  Float
:Default: ``0.3``


``mds_bal_minchunk``

:Description: Ceph will ignore 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-replay mode.
              ("hot 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 will randomly export subtrees between nodes (testing only).
:Type:  32-bit Integer
:Default: ``0``


``mds_thrash_fragments``

:Description: Ceph will randomly fragment or merge directories.
:Type:  32-bit Integer
:Default: ``0``


``mds_dump_cache_on_map``

:Description: Ceph will dump the MDS cache contents to a file on each MDSMap.
:Type:  Boolean
:Default:  ``false``


``mds_dump_cache_after_rejoin``

:Description: Ceph will dump MDS cache contents to a file after 
              rejoining the cache (during recovery).
              
:Type:  Boolean
:Default:  ``false``


``mds_verify_scatter``

:Description: Ceph will assert that various scatter/gather invariants 
              are ``true`` (developers only).
              
:Type:  Boolean
:Default:  ``false``


``mds_debug_scatterstat``

:Description: Ceph will assert that various recursive stat invariants 
              are ``true`` (for developers only).
              
:Type:  Boolean
:Default:  ``false``


``mds_debug_frag``

:Description: Ceph will verify directory fragmentation invariants 
              when convenient (developers only).
              
:Type:  Boolean
:Default:  ``false``


``mds_debug_auth_pins``

:Description: The debug auth pin invariants (for developers only).
:Type:  Boolean
:Default:  ``false``


``mds_debug_subtrees``

:Description: The debug subtree invariants (for developers only).
:Type:  Boolean
:Default:  ``false``


``mds_kill_mdstable_at``

:Description: Ceph will inject MDS failure in MDSTable code 
              (for developers only).
              
:Type:  32-bit Integer
:Default: ``0``


``mds_kill_export_at``

:Description: Ceph will inject MDS failure in the subtree export code 
              (for developers only).
              
:Type:  32-bit Integer
:Default: ``0``


``mds_kill_import_at``

:Description: Ceph will inject MDS failure in the subtree import code 
              (for developers only).
              
:Type:  32-bit Integer
:Default: ``0``


``mds_kill_link_at``

:Description: Ceph will inject MDS failure in hard link code 
              (for developers only).
              
:Type:  32-bit Integer
:Default: ``0``


``mds_kill_rename_at``

:Description: Ceph will inject MDS failure in the rename code 
              (for developers only).
              
:Type:  32-bit Integer
:Default: ``0``


``mds_wipe_sessions``

:Description: Ceph will delete all client sessions on startup 
              (for testing only).
              
:Type:  Boolean
:Default: ``false``


``mds_wipe_ino_prealloc``

:Description: Ceph will delete ino preallocation metadata on startup 
              (for testing only).
              
:Type:  Boolean
:Default: ``false``


``mds_skip_ino``

:Description: The number of inode numbers to skip on startup 
              (for testing only).
              
:Type:  32-bit Integer
:Default: ``0``


``mds_min_caps_per_client``

:Description: Set the minimum number of capabilities a client may hold.
:Type: Integer
:Default: ``100``


``mds_max_ratio_caps_per_client``

:Description: Set the maximum ratio of current caps that may be recalled during MDS cache pressure.
:Type: Float
:Default: ``0.8``