ceph/doc/mgr/localpool.rst

   1 Local Pool Module
   2 =================
   3
   4 The *localpool* module can automatically create RADOS pools that are
   5 localized to a subset of the overall cluster.  For example, by default, it will
   6 create a pool for each distinct ``rack`` in the cluster.  This can be useful for
   7 deployments where it is desirable to distribute some data locally and other data
   8 globally across the cluster.  One use-case is measuring performance and testing
   9 behavior of specific drive, NIC, or chassis models in isolation.
  10
  11 Enabling
  12 --------
  13
  14 The *localpool* module is enabled with::
  15
  16   ceph mgr module enable localpool
  17
  18 Configuring
  19 -----------
  20
  21 The *localpool* module understands the following options:
  22
  23 * **subtree** (default: `rack`): which CRUSH subtree type the module
  24   should create a pool for.
  25 * **failure_domain** (default: `host`): what failure domain we should
  26   separate data replicas across.
  27 * **pg_num** (default: `128`): number of PGs to create for each pool
  28 * **num_rep** (default: `3`): number of replicas for each pool.
  29   (Currently, pools are always replicated.)
  30 * **min_size** (default: none): value to set min_size to (unchanged from Ceph's default if this option is not set)
  31 * **prefix** (default: `by-$subtreetype-`): prefix for the pool name.
  32
  33 These options are set via the config-key interface.  For example, to
  34 change the replication level to 2x with only 64 PGs, ::
  35
  36   ceph config set mgr mgr/localpool/num_rep 2
  37   ceph config set mgr mgr/localpool/pg_num 64