mirror of
https://github.com/ceph/ceph
synced 2024-12-22 19:34:30 +00:00
181 lines
8.7 KiB
ReStructuredText
181 lines
8.7 KiB
ReStructuredText
==========================
|
|
Ceph Configuration Files
|
|
==========================
|
|
When you start the Ceph service, the initialization process activates a series
|
|
of daemons that run in the background. The hosts in a typical RADOS cluster run
|
|
at least one of three processes or daemons:
|
|
|
|
- RADOS (``ceph-osd``)
|
|
- Monitor (``ceph-mon``)
|
|
- Metadata Server (``ceph-mds``)
|
|
|
|
Each process or daemon looks for a ``ceph.conf`` file that provides their
|
|
configuration settings. The default ``ceph.conf`` locations in sequential
|
|
order include:
|
|
|
|
1. ``$CEPH_CONF`` (*i.e.,* the path following
|
|
the ``$CEPH_CONF`` environment variable)
|
|
2. ``-c path/path`` (*i.e.,* the ``-c`` command line argument)
|
|
3. ``/etc/ceph/ceph.conf``
|
|
4. ``~/.ceph/config``
|
|
5. ``./ceph.conf`` (*i.e.,* in the current working directory)
|
|
|
|
The ``ceph.conf`` file provides the settings for each Ceph daemon. Once you
|
|
have installed the Ceph packages on the OSD Cluster hosts, you need to create
|
|
a ``ceph.conf`` file to configure your OSD cluster.
|
|
|
|
Creating ``ceph.conf``
|
|
----------------------
|
|
The ``ceph.conf`` file defines:
|
|
|
|
- Cluster Membership
|
|
- Host Names
|
|
- Paths to Hosts
|
|
- Runtime Options
|
|
|
|
You can add comments to the ``ceph.conf`` file by preceding comments with
|
|
a semi-colon (;). For example::
|
|
|
|
; <--A semi-colon precedes a comment
|
|
; A comment may be anything, and always follows a semi-colon on each line.
|
|
; We recommend that you provide comments in your configuration file(s).
|
|
|
|
Configuration File Basics
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
The ``ceph.conf`` file configures each instance of the three common processes
|
|
in a RADOS cluster.
|
|
|
|
+-----------------+--------------+--------------+-----------------+-------------------------------------------------+
|
|
| Setting Scope | Process | Setting | Instance Naming | Description |
|
|
+=================+==============+==============+=================+=================================================+
|
|
| All Modules | All | ``[global]`` | N/A | Settings affect all instances of all daemons. |
|
|
+-----------------+--------------+--------------+-----------------+-------------------------------------------------+
|
|
| RADOS | ``ceph-osd`` | ``[osd]`` | Numeric | Settings affect RADOS instances only. |
|
|
+-----------------+--------------+--------------+-----------------+-------------------------------------------------+
|
|
| Monitor | ``ceph-mon`` | ``[mon]`` | Alphanumeric | Settings affect monitor instances only. |
|
|
+-----------------+--------------+--------------+-----------------+-------------------------------------------------+
|
|
| Metadata Server | ``ceph-mds`` | ``[mds]`` | Alphanumeric | Settings affect MDS instances only. |
|
|
+-----------------+--------------+--------------+-----------------+-------------------------------------------------+
|
|
|
|
Metavariables
|
|
~~~~~~~~~~~~~
|
|
The configuration system supports certain 'metavariables,' which are typically
|
|
used in ``[global]`` or process/daemon settings. If metavariables occur inside
|
|
a configuration value, Ceph expands them into a concrete value--similar to how
|
|
Bash shell expansion works.
|
|
|
|
There are a few different metavariables:
|
|
|
|
+--------------+----------------------------------------------------------------------------------------------------------+
|
|
| Metavariable | Description |
|
|
+==============+==========================================================================================================+
|
|
| ``$host`` | Expands to the host name of the current daemon. |
|
|
+--------------+----------------------------------------------------------------------------------------------------------+
|
|
| ``$type`` | Expands to one of ``mds``, ``osd``, or ``mon``, depending on the type of the current daemon. |
|
|
+--------------+----------------------------------------------------------------------------------------------------------+
|
|
| ``$id`` | Expands to the daemon identifier. For ``osd.0``, this would be ``0``; for ``mds.a``, it would be ``a``. |
|
|
+--------------+----------------------------------------------------------------------------------------------------------+
|
|
| ``$num`` | Same as ``$id``. |
|
|
+--------------+----------------------------------------------------------------------------------------------------------+
|
|
| ``$name`` | Expands to ``$type.$id``. |
|
|
+--------------+----------------------------------------------------------------------------------------------------------+
|
|
| ``$cluster`` | Expands to the cluster name. Useful when running multiple clusters on the same hardware. |
|
|
+--------------+----------------------------------------------------------------------------------------------------------+
|
|
|
|
Global Settings
|
|
~~~~~~~~~~~~~~~
|
|
The Ceph configuration file supports a hierarchy of settings, where child
|
|
settings inherit the settings of the parent. Global settings affect all
|
|
instances of all processes in the cluster. Use the ``[global]`` setting for
|
|
values that are common for all hosts in the cluster. You can override each
|
|
``[global]`` setting by:
|
|
|
|
1. Changing the setting in a particular ``[group]``.
|
|
2. Changing the setting in a particular process type (*e.g.,* ``[osd]``, ``[mon]``, ``[mds]`` ).
|
|
3. Changing the setting in a particular process (*e.g.,* ``[osd.1]`` )
|
|
|
|
Overriding a global setting affects all child processes, except those that
|
|
you specifically override. For example::
|
|
|
|
[global]
|
|
; Enable authentication between hosts within the cluster.
|
|
auth supported = cephx
|
|
|
|
Process/Daemon Settings
|
|
~~~~~~~~~~~~~~~~~~~~~~~
|
|
You can specify settings that apply to a particular type of process. When you
|
|
specify settings under ``[osd]``, ``[mon]`` or ``[mds]`` without specifying a
|
|
particular instance, the setting will apply to all OSDs, monitors or metadata
|
|
daemons respectively.
|
|
|
|
Instance Settings
|
|
~~~~~~~~~~~~~~~~~
|
|
You may specify settings for particular instances of an daemon. You may specify
|
|
an instance by entering its type, delimited by a period (.) and by the
|
|
instance ID. The instance ID for an OSD is always numeric, but it may be
|
|
alphanumeric for monitors and metadata servers. ::
|
|
|
|
[osd.1]
|
|
; settings affect osd.1 only.
|
|
[mon.a1]
|
|
; settings affect mon.a1 only.
|
|
[mds.b2]
|
|
; settings affect mds.b2 only.
|
|
|
|
``host`` and ``addr`` Settings
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
The :doc:`/install/hardware-recommendations` section provides some hardware guidelines for
|
|
configuring the cluster. It is possible for a single host to run
|
|
multiple daemons. For example, a single host with multiple disks or
|
|
RAIDs may run one ``ceph-osd`` for each disk or RAID. Additionally, a
|
|
host may run both a ``ceph-mon`` and an ``ceph-osd`` daemon on the
|
|
same host. Ideally, you will have a host for a particular type of
|
|
process. For example, one host may run ``ceph-osd`` daemons, another
|
|
host may run a ``ceph-mds`` daemon, and other hosts may run
|
|
``ceph-mon`` daemons.
|
|
|
|
Each host has a name identified by the ``host`` setting, and a network
|
|
location (i.e., domain name or IP address) identified by the ``addr``
|
|
setting. For example::
|
|
|
|
[osd.1]
|
|
host = hostNumber1
|
|
addr = 150.140.130.120:1100
|
|
[osd.2]
|
|
host = hostNumber1
|
|
addr = 150.140.130.120:1102
|
|
|
|
|
|
Monitor Configuration
|
|
~~~~~~~~~~~~~~~~~~~~~
|
|
Ceph typically deploys with 3 monitors to ensure high availability should a
|
|
monitor instance crash. An odd number of monitors (3) ensures that the Paxos
|
|
algorithm can determine which version of the cluster map is the most accurate.
|
|
|
|
.. note:: You may deploy Ceph with a single monitor, but if the instance fails,
|
|
the lack of a monitor may interrupt data service availability.
|
|
|
|
Ceph monitors typically listen on port ``6789``.
|
|
|
|
Example Configuration File
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
.. literalinclude:: demo-ceph.conf
|
|
:language: ini
|
|
|
|
Configuration File Deployment Options
|
|
-------------------------------------
|
|
The most common way to deploy the ``ceph.conf`` file in a cluster is to have
|
|
all hosts share the same configuration file.
|
|
|
|
You may create a ``ceph.conf`` file for each host if you wish, or
|
|
specify a particular ``ceph.conf`` file for a subset of hosts within
|
|
the cluster. However, using per-host ``ceph.conf`` configuration files
|
|
imposes a maintenance burden as the cluster grows. In a typical
|
|
deployment, an administrator creates a ``ceph.conf`` file on the
|
|
Administration host and then copies that file to each OSD Cluster
|
|
host.
|
|
|
|
The current cluster deployment script, ``mkcephfs``, does not make copies of the
|
|
``ceph.conf``. You must copy the file manually.
|