determine data placement for a pool. For large clusters, you will likely create
many pools where each pool may have its own CRUSH ruleset and rules. The default
CRUSH map has a rule for each pool, and one ruleset assigned to each of the
-default pools, which include:
-
-- ``data``
-- ``metadata``
-- ``rbd``
+default pools.
.. note:: In most cases, you will not need to modify the default rules. When
you create a new pool, its default ruleset is ``0``.
Placement group IDs consist of the pool number (not pool name) followed
by a period (.) and the placement group ID--a hexadecimal number. You
can view pool numbers and their names from the output of ``ceph osd
- lspools``. The default pool names ``data``, ``metadata`` and ``rbd``
- correspond to pool numbers ``0``, ``1`` and ``2`` respectively. A fully
- qualified placement group ID has the following form::
+ lspools``. For example, the default pool ``rbd`` corresponds to
+ pool number ``0``. A fully qualified placement group ID has the
+ following form::
{pool-num}.{pg-id}
ceph osd lspools
-The default pools include:
-
-- ``data``
-- ``metadata``
-- ``rbd``
+On a freshly installed cluster, only the ``rbd`` pool exists.
.. _createpool:
Pool
----
-A pool is a logical partition where users store data. By default, a Ceph Storage
-Cluster has `pools`_ for ``data``, ``rbd`` and ``metadata`` (metadata server).
+A pool is a logical partition where users store data.
In Ceph deployments, it is common to create a pool as a logical partition for
similar types of data. For example, when deploying Ceph as a backend for
OpenStack, a typical deployment would have pools for volumes, images, backups