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). Once the rank is deactivated, the MDS daemon will rejoin the
 103 cluster as a standby.
 104 ``<role>`` can take one of three forms:
 105
 106 ::
 107
 108     <fs_name>:<rank>
 109     <fs_id>:<rank>
 110     <rank>
 111
 112 Use ``mds deactivate`` in conjunction with adjustments to ``max_mds`` to
 113 shrink an MDS cluster.  See :doc:`/cephfs/multimds`
 114
 115 ::
 116
 117     tell mds.<daemon name>
 118
 119 ::
 120
 121     mds metadata <gid/name/role>
 122
 123 ::
 124
 125     mds repaired <role>
 126
 127
 128 Global settings
 129 ---------------
 130
 131 ::
 132
 133     fs dump
 134
 135 ::
 136
 137     fs flag set <flag name> <flag val> [<confirmation string>]
 138
 139 "flag name" must be one of ['enable_multiple']
 140
 141 Some flags require you to confirm your intentions with "--yes-i-really-mean-it"
 142 or a similar string they will prompt you with. Consider these actions carefully
 143 before proceeding; they are placed on especially dangerous activities.
 144
 145
 146 Advanced
 147 --------
 148
 149 These commands are not required in normal operation, and exist
 150 for use in exceptional circumstances.  Incorrect use of these
 151 commands may cause serious problems, such as an inaccessible
 152 filesystem.
 153
 154 ::
 155
 156     mds compat rm_compat
 157
 158 ::
 159
 160     mds compat rm_incompat
 161
 162 ::
 163
 164     mds compat show
 165
 166 ::
 167
 168     mds getmap
 169
 170 ::
 171
 172     mds set_state
 173
 174 ::
 175
 176     mds rmfailed
 177
 178 Legacy
 179 ------
 180
 181 The ``ceph mds set`` command is the deprecated version of ``ceph fs set``,
 182 from before there was more than one filesystem per cluster. It operates
 183 on whichever filesystem is marked as the default (see ``ceph fs
 184 set-default``.)
 185
 186 ::
 187
 188     mds stat
 189     mds dump  # replaced by "fs get"
 190     mds stop  # replaced by "mds deactivate"
 191     mds set_max_mds # replaced by "fs set max_mds"
 192     mds set # replaced by "fs set"
 193     mds cluster_down  # replaced by "fs set cluster_down"
 194     mds cluster_up  # replaced by "fs set cluster_up"
 195     mds newfs # replaced by "fs new"
 196     mds add_data_pool # replaced by "fs add_data_pool"
 197     mds remove_data_pool #replaced by "fs remove_data_pool"
 198