ceph/doc/rados/configuration/common.rst

.. _ceph-conf-common-settings:

Common Settings
===============

The `Hardware Recommendations`_ section provides some hardware guidelines for
configuring a Ceph Storage Cluster. It is possible for a single :term:`Ceph
Node` to run multiple daemons. For example, a single node with multiple drives
may run one ``ceph-osd`` for each drive. Ideally, you will  have a node for a
particular type of process. For example, some nodes may run ``ceph-osd``
daemons, other nodes may run ``ceph-mds`` daemons, and still  other nodes may
run ``ceph-mon`` daemons.

Each node has a name identified by the ``host`` setting. Monitors also specify
a network address and port (i.e., domain name or IP address) identified by the
``addr`` setting.  A basic configuration file will typically specify only
minimal settings for each instance of monitor daemons. For example:

.. code-block:: ini

	[global]
	mon_initial_members = ceph1
	mon_host = 10.0.0.1


.. important:: The ``host`` setting is the short name of the node (i.e., not
   an fqdn). It is **NOT** an IP address either.  Enter ``hostname -s`` on
   the command line to retrieve the name of the node. Do not use ``host``
   settings for anything other than initial monitors unless you are deploying
   Ceph manually. You **MUST NOT** specify ``host`` under individual daemons
   when using deployment tools like ``chef`` or ``ceph-deploy``, as those tools
   will enter the appropriate values for you in the cluster map.


.. _ceph-network-config:

Networks
========

See the `Network Configuration Reference`_ for a detailed discussion about
configuring a network for use with Ceph.


Monitors
========

Ceph production clusters typically deploy with a minimum 3 :term:`Ceph Monitor`
daemons to ensure high availability should a monitor instance crash. At least
three (3) monitors ensures that the Paxos algorithm can determine which version
of the :term:`Ceph Cluster Map` is the most recent from a majority of Ceph
Monitors in the quorum.

.. note:: You may deploy Ceph with a single monitor, but if the instance fails,
	       the lack of other monitors may interrupt data service availability.

Ceph Monitors typically listen on port ``6789``. For example:

.. code-block:: ini

	[mon.a]
	host = hostName
	mon addr = 150.140.130.120:6789

By default, Ceph expects that you will store a monitor's data under the
following path::

	/var/lib/ceph/mon/$cluster-$id

You or a deployment tool (e.g., ``ceph-deploy``) must create the corresponding
directory. With metavariables fully  expressed and a cluster named "ceph", the
foregoing directory would evaluate to::

	/var/lib/ceph/mon/ceph-a

For additional details, see the `Monitor Config Reference`_.

.. _Monitor Config Reference: ../mon-config-ref


.. _ceph-osd-config:


Authentication
==============

.. versionadded:: Bobtail 0.56

For Bobtail (v 0.56) and beyond, you should expressly enable or disable
authentication in the ``[global]`` section of your Ceph configuration file. ::

	auth cluster required = cephx
	auth service required = cephx
	auth client required = cephx

Additionally, you should enable message signing. See `Cephx Config Reference`_ for details.

.. important:: When upgrading, we recommend expressly disabling authentication
   first, then perform the upgrade. Once the upgrade is complete, re-enable
   authentication.

.. _Cephx Config Reference: ../auth-config-ref


.. _ceph-monitor-config:


OSDs
====

Ceph production clusters typically deploy :term:`Ceph OSD Daemons` where one node
has one OSD daemon running a filestore on one storage drive. A typical
deployment specifies a journal size. For example:

.. code-block:: ini

	[osd]
	osd journal size = 10000

	[osd.0]
	host = {hostname} #manual deployments only.


By default, Ceph expects that you will store a Ceph OSD Daemon's data with the
following path::

	/var/lib/ceph/osd/$cluster-$id

You or a deployment tool (e.g., ``ceph-deploy``) must create the corresponding
directory. With metavariables fully  expressed and a cluster named "ceph", the
foregoing directory would evaluate to::

	/var/lib/ceph/osd/ceph-0

You may override this path using the ``osd data`` setting. We don't recommend
changing the default location. Create the default directory on your OSD host.

::

	ssh {osd-host}
	sudo mkdir /var/lib/ceph/osd/ceph-{osd-number}

The ``osd data`` path ideally leads to a mount point with a hard disk that is
separate from the hard disk storing and running the operating system and
daemons. If the OSD is for a disk other than the OS disk, prepare it for
use with Ceph, and mount it to the directory you just created::

	ssh {new-osd-host}
	sudo mkfs -t {fstype} /dev/{disk}
	sudo mount -o user_xattr /dev/{hdd} /var/lib/ceph/osd/ceph-{osd-number}

We recommend using the ``xfs`` file system when running
:command:`mkfs`.  (``btrfs`` and ``ext4`` are not recommended and no
longer tested.)

See the `OSD Config Reference`_ for additional configuration details.


Heartbeats
==========

During runtime operations, Ceph OSD Daemons check up on other Ceph OSD Daemons
and report their  findings to the Ceph Monitor. You do not have to provide any
settings. However, if you have network latency issues, you may wish to modify
the settings.

See `Configuring Monitor/OSD Interaction`_ for additional details.


.. _ceph-logging-and-debugging:

Logs / Debugging
================

Sometimes you may encounter issues with Ceph that require
modifying logging output and using Ceph's debugging. See `Debugging and
Logging`_ for details on log rotation.

.. _Debugging and Logging: ../../troubleshooting/log-and-debug


Example ceph.conf
=================

.. literalinclude:: demo-ceph.conf
   :language: ini

.. _ceph-runtime-config:



Running Multiple Clusters
=========================

With Ceph, you can run multiple Ceph Storage Clusters on the same hardware.
Running multiple clusters provides a higher level of isolation compared to
using different pools on the same cluster with different CRUSH rules. A
separate cluster will have separate monitor, OSD and metadata server processes.
When running Ceph with  default settings, the default cluster name is ``ceph``,
which means you would  save your Ceph configuration file with the file name
``ceph.conf`` in the  ``/etc/ceph`` default directory.

See `ceph-deploy new`_ for details.
.. _ceph-deploy new:../ceph-deploy-new

When you run multiple clusters, you must name your cluster and save the Ceph
configuration file with the name of the cluster. For example, a cluster named
``openstack`` will have a Ceph configuration file with the file name
``openstack.conf`` in the  ``/etc/ceph`` default directory.

.. important:: Cluster names must consist of letters a-z and digits 0-9 only.

Separate clusters imply separate data disks and journals, which are not shared
between clusters. Referring to `Metavariables`_, the ``$cluster``  metavariable
evaluates to the cluster name (i.e., ``openstack`` in the  foregoing example).
Various settings use the ``$cluster`` metavariable, including:

.. _Metavariables: ../ceph-conf#Metavariables

- ``keyring``
- ``admin socket``
- ``log file``
- ``pid file``
- ``mon data``
- ``mon cluster log file``
- ``osd data``
- ``osd journal``
- ``mds data``
- ``rgw data``

See `General Settings`_, `OSD Settings`_, `Monitor Settings`_, `MDS Settings`_,
`RGW Settings`_ and `Log Settings`_ for relevant path defaults that use the
``$cluster`` metavariable.

.. _General Settings: ../general-config-ref
.. _OSD Settings: ../osd-config-ref
.. _Monitor Settings: ../mon-config-ref
.. _MDS Settings: ../../../cephfs/mds-config-ref
.. _RGW Settings: ../../../radosgw/config-ref/
.. _Log Settings: ../../troubleshooting/log-and-debug


When creating default directories or files, you should use the cluster
name at the appropriate places in the path. For example::

	sudo mkdir /var/lib/ceph/osd/openstack-0
	sudo mkdir /var/lib/ceph/mon/openstack-a

.. important:: When running monitors on the same host, you should use
   different ports. By default, monitors use port 6789. If you already
   have monitors using port 6789, use a different port for your other cluster(s).

To invoke a cluster other than the default ``ceph`` cluster, use the
``-c {filename}.conf`` option with the ``ceph`` command. For example::

	ceph -c {cluster-name}.conf health
	ceph -c openstack.conf health


.. _Hardware Recommendations: ../../../start/hardware-recommendations
.. _Network Configuration Reference: ../network-config-ref
.. _OSD Config Reference: ../osd-config-ref
.. _Configuring Monitor/OSD Interaction: ../mon-osd-interaction
.. _ceph-deploy new: ../../deployment/ceph-deploy-new#naming-a-cluster