Notice

This document is for a development version of Ceph.

MDS Config Reference

mds_cache_mid

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

type

float

default

0.7

mds_dir_max_commit_size

The maximum size of a directory update before Ceph breaks it into smaller transactions (MB).

type

int

default

10

mds_decay_halflife

rate of decay for temperature counters on each directory for balancing

type

float

default

5.0

mds_beacon_interval

interval in seconds between MDS beacon messages sent to monitors

type

float

default

4.0

mds_beacon_grace

The interval without beacons before Ceph declares an MDS laggy (and possibly replace it).

type

float

default

15.0

mon_mds_blocklist_interval

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

1 day

min

1_hr

mds_reconnect_timeout

timeout in seconds to wait for clients to reconnect during MDS reconnect recovery state

type

float

default

45.0

mds_tick_interval

How frequently the MDS performs internal periodic tasks.

type

float

default

5.0

mds_dirstat_min_interval

The minimum interval (in seconds) to try to avoid propagating recursive stats up the tree.

type

float

default

1.0

mds_scatter_nudge_interval

How quickly dirstat changes propagate up.

type

float

default

5.0

mds_client_prealloc_inos

The number of inode numbers to preallocate per client session.

type

int

default

1000

mds_early_reply

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

type

bool

default

true

mds_default_dir_hash

The function to use for hashing files across directory fragments.

type

int

default

2

mds_log_skip_corrupt_events

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

type

bool

default

false

mds_log_max_events

The maximum events in the journal before we initiate trimming. Set to -1 to disable limits.

type

int

default

-1

mds_log_max_segments

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

type

uint

default

128

mds_bal_sample_interval

Determines how frequently to sample directory temperature (for fragmentation decisions).

type

float

default

3.0

mds_bal_replicate_threshold

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

type

float

default

8000.0

mds_bal_unreplicate_threshold

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

type

float

default

0.0

mds_bal_split_size

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

type

int

default

10000

mds_bal_split_rd

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

type

float

default

25000.0

mds_bal_split_wr

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

type

float

default

10000.0

mds_bal_split_bits

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

type

int

default

3

allowed range

[1, 24]

mds_bal_merge_size

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

type

int

default

50

mds_bal_interval

The frequency (in seconds) of workload exchanges between MDSs.

type

int

default

10

mds_bal_fragment_interval

The delay (in seconds) between a fragment being eligible for split or merge and executing the fragmentation change.

type

int

default

5

mds_bal_fragment_fast_factor

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

The maximum size of a fragment before any new entries are rejected with ENOSPC.

type

int

default

100000

mds_bal_idle_threshold

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

type

float

default

0.0

mds_bal_max

The number of iterations to run balancer before Ceph stops. (used for testing purposes only)

type

int

default

-1

mds_bal_max_until

The number of seconds to run balancer before Ceph stops. (used for testing purposes only)

type

int

default

-1

mds_bal_mode

The method for calculating MDS load.

  • 0 = Hybrid.

  • 1 = Request rate and latency.

  • 2 = CPU load.

type

int

default

0

mds_bal_min_rebalance

The minimum subtree temperature before Ceph migrates.

type

float

default

0.1

mds_bal_min_start

The minimum subtree temperature before Ceph searches a subtree.

type

float

default

0.2

mds_bal_need_min

The minimum fraction of target subtree size to accept.

type

float

default

0.8

mds_bal_need_max

The maximum fraction of target subtree size to accept.

type

float

default

1.2

mds_bal_midchunk

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

type

float

default

0.3

mds_bal_minchunk

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

type

float

default

0.001

mds_replay_interval

The journal poll interval when in standby-replay mode. (“hot standby”)

type

float

default

1.0

mds_shutdown_check

The interval for polling the cache during MDS shutdown.

type

int

default

0

mds_thrash_exports

Ceph will randomly export subtrees between nodes (testing only).

type

int

default

0

mds_thrash_fragments

Ceph will randomly fragment or merge directories.

type

int

default

0

mds_dump_cache_on_map

Ceph will dump the MDS cache contents to a file on each MDSMap.

type

bool

default

false

mds_dump_cache_after_rejoin

Ceph will dump MDS cache contents to a file after rejoining the cache (during recovery).

type

bool

default

false

mds_verify_scatter

Ceph will assert that various scatter/gather invariants are true (developers only).

type

bool

default

false

mds_debug_scatterstat

Ceph will assert that various recursive stat invariants are true (for developers only).

type

bool

default

false

mds_debug_frag

Ceph will verify directory fragmentation invariants when convenient (developers only).

type

bool

default

false

mds_debug_auth_pins

The debug auth pin invariants (for developers only).

type

bool

default

false

mds_debug_subtrees

The debug subtree invariants (for developers only).

type

bool

default

false

mds_kill_mdstable_at

Ceph will inject MDS failure in MDSTable code (for developers only).

type

int

default

0

mds_kill_export_at

Ceph will inject MDS failure in the subtree export code (for developers only).

type

int

default

0

mds_kill_import_at

Ceph will inject MDS failure in the subtree import code (for developers only).

type

int

default

0

Ceph will inject MDS failure in hard link code (for developers only).

type

int

default

0

mds_kill_rename_at

Ceph will inject MDS failure in the rename code (for developers only).

type

int

default

0

mds_wipe_sessions

Ceph will delete all client sessions on startup (for testing only).

type

bool

default

false

mds_wipe_ino_prealloc

Ceph will delete ino preallocation metadata on startup (for testing only).

type

bool

default

false

mds_skip_ino

The number of inode numbers to skip on startup (for testing only).

type

int

default

0

mds_min_caps_per_client

minimum number of capabilities a client may hold

type

uint

default

100