ceph/doc/cephfs/administration.rst

   1
   2 CephFS Administrative commands
   3 ==============================
   4
   5 Filesystems
   6 -----------
   7
   8 These commands operate on the CephFS filesystems in your Ceph cluster.
   9 Note that by default only one filesystem is permitted: to enable
  10 creation of multiple filesystems use ``ceph fs flag set enable_multiple true``.
  11
  12 ::
  13
  14     fs new <filesystem name> <metadata pool name> <data pool name>
  15
  16 ::
  17
  18     fs ls
  19
  20 ::
  21
  22     fs rm <filesystem name> [--yes-i-really-mean-it]
  23
  24 ::
  25
  26     fs reset <filesystem name>
  27
  28 ::
  29
  30     fs get <filesystem name>
  31
  32 ::
  33
  34     fs set <filesystem name> <var> <val>
  35
  36 ::
  37
  38     fs add_data_pool <filesystem name> <pool name/id>
  39
  40 ::
  41
  42     fs rm_data_pool <filesystem name> <pool name/id>
  43
  44
  45 Settings
  46 --------
  47
  48 ::
  49
  50     fs set <fs name> max_file_size <size in bytes>
  51
  52 CephFS has a configurable maximum file size, and it's 1TB by default.
  53 You may wish to set this limit higher if you expect to store large files
  54 in CephFS. It is a 64-bit field.
  55
  56 Setting ``max_file_size`` to 0 does not disable the limit. It would
  57 simply limit clients to only creating empty files.
  58
  59
  60 Maximum file sizes and performance
  61 ----------------------------------
  62
  63 CephFS enforces the maximum file size limit at the point of appending to
  64 files or setting their size. It does not affect how anything is stored.
  65
  66 When users create a file of an enormous size (without necessarily
  67 writing any data to it), some operations (such as deletes) cause the MDS
  68 to have to do a large number of operations to check if any of the RADOS
  69 objects within the range that could exist (according to the file size)
  70 really existed.
  71
  72 The ``max_file_size`` setting prevents users from creating files that
  73 appear to be eg. exabytes in size, causing load on the MDS as it tries
  74 to enumerate the objects during operations like stats or deletes.
  75
  76
  77 Daemons
  78 -------
  79
  80 These commands act on specific mds daemons or ranks.
  81
  82 ::
  83
  84     mds fail <gid/name/role>
  85
  86 Mark an MDS daemon as failed.  This is equivalent to what the cluster
  87 would do if an MDS daemon had failed to send a message to the mon
  88 for ``mds_beacon_grace`` second.  If the daemon was active and a suitable
  89 standby is available, using ``mds fail`` will force a failover to the standby.
  90
  91 If the MDS daemon was in reality still running, then using ``mds fail``
  92 will cause the daemon to restart.  If it was active and a standby was
  93 available, then the "failed" daemon will return as a standby.
  94
  95 ::
  96
  97     mds deactivate <role>
  98
  99 Deactivate an MDS, causing it to flush its entire journal to
 100 backing RADOS objects and close all open client sessions. Deactivating an MDS
 101 is primarily intended for bringing down a rank after reducing the number of
 102 active MDS (max_mds).
 103
 104 Use ``mds deactivate`` in conjunction with adjustments to ``max_mds`` to
 105 shrink an MDS cluster.  See :doc:`/cephfs/multimds`
 106
 107 ::
 108
 109     tell mds.<daemon name>
 110
 111 ::
 112
 113     mds metadata <gid/name/role>
 114
 115 ::
 116
 117     mds repaired <role>
 118
 119
 120 Global settings
 121 ---------------
 122
 123 ::
 124
 125     fs dump
 126
 127 ::
 128
 129     fs flag set <flag name> <flag val> [<confirmation string>]
 130
 131 "flag name" must be one of ['enable_multiple']
 132
 133 Some flags require you to confirm your intentions with "--yes-i-really-mean-it"
 134 or a similar string they will prompt you with. Consider these actions carefully
 135 before proceeding; they are placed on especially dangerous activities.
 136
 137
 138 Advanced
 139 --------
 140
 141 These commands are not required in normal operation, and exist
 142 for use in exceptional circumstances.  Incorrect use of these
 143 commands may cause serious problems, such as an inaccessible
 144 filesystem.
 145
 146 ::
 147
 148     mds compat rm_compat
 149
 150 ::
 151
 152     mds compat rm_incompat
 153
 154 ::
 155
 156     mds compat show
 157
 158 ::
 159
 160     mds getmap
 161
 162 ::
 163
 164     mds set_state
 165
 166 ::
 167
 168     mds rmfailed
 169
 170 Legacy
 171 ------
 172
 173 The ``ceph mds set`` command is the deprecated version of ``ceph fs set``,
 174 from before there was more than one filesystem per cluster. It operates
 175 on whichever filesystem is marked as the default (see ``ceph fs
 176 set-default``.)
 177
 178 ::
 179
 180     mds stat
 181     mds dump  # replaced by "fs get"
 182     mds stop  # replaced by "mds deactivate"
 183     mds set_max_mds # replaced by "fs set max_mds"
 184     mds set # replaced by "fs set"
 185     mds cluster_down  # replaced by "fs set cluster_down"
 186     mds cluster_up  # replaced by "fs set cluster_up"
 187     mds newfs # replaced by "fs new"
 188     mds add_data_pool # replaced by "fs add_data_pool"
 189     mds remove_data_pool #replaced by "fs remove_data_pool"
 190