MDS Config Reference¶

mon force standby active

Description: If true monitors force standby-replay to be active. Set under [mon] or [global].
Type: Boolean
Default: true

mds cache memory limit

Description: The memory limit the MDS should enforce for its cache. Administrators should use this instead of mds cache size.
Type: 64-bit Integer Unsigned
Default: 1073741824

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 size

Description: The number of inodes to cache. A value of 0 indicates an unlimited number. It is recommended to use mds_cache_memory_limit to 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 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: 90

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 blacklist interval

Description: The blacklist duration for failed MDSs in the OSD map. Note, this controls how long failed MDS daemons will stay in the OSDMap blacklist. It has no effect on how long something is blacklisted when the administrator blacklists it manually. For example, ceph osd blacklist add will still use the default blacklist 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 iteration 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 standby for name

Description: An MDS daemon will standby for another MDS daemon of the name specified in this setting.
Type: String
Default: N/A

mds standby for rank

Description: An MDS daemon will standby for an MDS daemon of this rank.
Type: 32-bit Integer
Default: -1

mds standby replay

Description: Determines whether a ceph-mds daemon should poll and replay the log of an active MDS (hot standby).
Type: Boolean
Default: false

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