ceph/doc/start/quick-ceph-deploy.rst

=============================
 Storage Cluster Quick Start
=============================

If you haven't completed your `Preflight Checklist`_, do that first. This
**Quick Start** sets up a :term:`Ceph Storage Cluster` using ``ceph-deploy``
on your admin node. Create a three Ceph Node cluster so you can
explore Ceph functionality.

.. include:: quick-common.rst

As a first exercise, create a Ceph Storage Cluster with one Ceph Monitor and two
Ceph OSD Daemons. Once the cluster reaches a ``active + clean`` state, expand it
by adding a third Ceph OSD Daemon, a Metadata Server and two more Ceph Monitors.
For best results, create a directory on your admin node node for maintaining the
configuration files and keys that ``ceph-deploy`` generates for your cluster. ::

	mkdir my-cluster
	cd my-cluster

The ``ceph-deploy`` utility will output files to the current directory. Ensure you
are in this directory when executing ``ceph-deploy``.

.. important:: Do not call ``ceph-deploy`` with ``sudo`` or run it as ``root``
   if you are logged in as a different user, because it will not issue ``sudo``
   commands needed on the remote host.

.. topic:: Disable ``requiretty``

   On some distributions (e.g., CentOS), you may receive an error while trying
   to execute ``ceph-deploy`` commands. If ``requiretty`` is set
   by default, disable it by executing ``sudo visudo`` and locate the
   ``Defaults requiretty`` setting. Change it to ``Defaults:ceph !requiretty`` to
   ensure that ``ceph-deploy`` can connect using the ``ceph`` user and execute
   commands with ``sudo``.

Create a Cluster
================

If at any point you run into trouble and you want to start over, execute
the following to purge the configuration::

	ceph-deploy purgedata {ceph-node} [{ceph-node}]
	ceph-deploy forgetkeys

To purge the Ceph packages too, you may also execute::

	ceph-deploy purge {ceph-node} [{ceph-node}]

If you execute ``purge``, you must re-install Ceph.

On your admin node from the directory you created for holding your
configuration details, perform the following steps using ``ceph-deploy``.

#. Create the cluster. ::

	ceph-deploy new {initial-monitor-node(s)}

   For example::

	ceph-deploy new node1

   Check the output of ``ceph-deploy`` with ``ls`` and ``cat`` in the current
   directory. You should see a Ceph configuration file, a monitor secret
   keyring, and a log file for the new cluster.  See `ceph-deploy new -h`_
   for additional details.

#. Change the default number of replicas in the Ceph configuration file from
   ``3`` to ``2`` so that Ceph can achieve an ``active + clean`` state with
   just two Ceph OSDs. Add the following line under the ``[global]`` section::

	osd pool default size = 2

#. If you have more than one network interface, add the ``public network``
   setting under the ``[global]`` section of your Ceph configuration file.
   See the `Network Configuration Reference`_ for details. ::

	public network = {ip-address}/{netmask}

#. Install Ceph. ::

	ceph-deploy install {ceph-node}[{ceph-node} ...]

   For example::

	ceph-deploy install admin-node node1 node2 node3

   The ``ceph-deploy`` utility will install Ceph on each node.
   **NOTE**: If you use ``ceph-deploy purge``, you must re-execute this step
   to re-install Ceph.


#. Add the initial monitor(s) and gather the keys (new in
   ``ceph-deploy`` v1.1.3). ::

	ceph-deploy mon create-initial

   **Note:** In earlier versions of ``ceph-deploy``, you must create the
   initial monitor(s) and gather keys in two discrete steps. First, create
   the monitor. ::

	ceph-deploy mon create {ceph-node}

   For example::

	ceph-deploy mon create node1

   Then, gather the keys. ::

	ceph-deploy gatherkeys {ceph-node}

   For example::

	ceph-deploy gatherkeys node1

   Once you complete the process, your local directory should have the following
   keyrings:

   - ``{cluster-name}.client.admin.keyring``
   - ``{cluster-name}.bootstrap-osd.keyring``
   - ``{cluster-name}.bootstrap-mds.keyring``


#. Add two OSDs. For fast setup, this quick start uses a directory rather
   than an entire disk per Ceph OSD Daemon. See `ceph-deploy osd`_ for
   details on using separate disks/partitions for OSDs and journals.
   Login to the Ceph Nodes and create a directory for
   the Ceph OSD Daemon. ::

	ssh node2
	sudo mkdir /var/local/osd0
	exit

	ssh node3
	sudo mkdir /var/local/osd1
	exit

   Then, from your admin node, use ``ceph-deploy`` to prepare the OSDs. ::

	ceph-deploy osd prepare {ceph-node}:/path/to/directory

   For example::

	ceph-deploy osd prepare node2:/var/local/osd0 node3:/var/local/osd1

   Finally, activate the OSDs. ::

	ceph-deploy osd activate {ceph-node}:/path/to/directory

   For example::

	ceph-deploy osd activate node2:/var/local/osd0 node3:/var/local/osd1


#. Use ``ceph-deploy`` to copy the configuration file and admin key to
   your admin node and your Ceph Nodes so that you can use the ``ceph``
   CLI without having to specify the monitor address and
   ``ceph.client.admin.keyring`` each time you execute a command. ::

	ceph-deploy admin {admin-node} {ceph-node}

   For example::

	ceph-deploy admin admin-node node1 node2 node3


   When ``ceph-deploy`` is talking to the local admin host (``admin-node``),
   it must be reachable by its hostname. If necessary, modify ``/etc/hosts``
   to add the name of the admin host.

#. Ensure that you have the correct permissions for the
   ``ceph.client.admin.keyring``. ::

	sudo chmod +r /etc/ceph/ceph.client.admin.keyring

#. Check your cluster's health. ::

	ceph health

   Your cluster should return an ``active + clean`` state when it
   has finished peering.


Operating Your Cluster
======================

Deploying a Ceph cluster with ``ceph-deploy`` automatically starts the cluster.
To operate the cluster daemons with Debian/Ubuntu distributions, see
`Running Ceph with Upstart`_.  To operate the cluster daemons with CentOS,
Red Hat, Fedora, and SLES distributions, see `Running Ceph with sysvinit`_.

To learn more about peering and cluster health, see `Monitoring a Cluster`_.
To learn more about Ceph OSD Daemon and placement group health, see
`Monitoring OSDs and PGs`_. To learn more about managing users, see
`User Management`_.

Once you deploy a Ceph cluster, you can try out some of the administration
functionality, the ``rados`` object store command line, and then proceed to
Quick Start guides for Ceph Block Device, Ceph Filesystem, and the Ceph Object
Gateway.


Expanding Your Cluster
======================

Once you have a basic cluster up and running, the next step is to expand
cluster. Add a Ceph OSD Daemon and a Ceph Metadata Server to ``node1``.
Then add a Ceph Monitor to ``node2`` and  ``node3`` to establish a
quorum of Ceph Monitors.

.. ditaa::
           /------------------\         /----------------\
           |    ceph–deploy   |         |     node1      |
           |    Admin Node    |         | cCCC           |
           |                  +-------->+   mon.node1    |
           |                  |         |     osd.2      |
           |                  |         |   mds.node1    |
           \---------+--------/         \----------------/
                     |
                     |                  /----------------\
                     |                  |     node2      |
                     |                  | cCCC           |
                     +----------------->+                |
                     |                  |     osd.0      |
                     |                  |   mon.node2    |
                     |                  \----------------/
                     |
                     |                  /----------------\
                     |                  |     node3      |
                     |                  | cCCC           |
                     +----------------->+                |
                                        |     osd.1      |
                                        |   mon.node3    |
                                        \----------------/

Adding an OSD
-------------

Since you are running a 3-node cluster for demonstration purposes, add the OSD
to the monitor node. ::

	ssh node1
	sudo mkdir /var/local/osd2
	exit

Then, from your ``ceph-deploy`` node, prepare the OSD. ::

	ceph-deploy osd prepare {ceph-node}:/path/to/directory

For example::

	ceph-deploy osd prepare node1:/var/local/osd2

Finally, activate the OSDs. ::

	ceph-deploy osd activate {ceph-node}:/path/to/directory

For example::

	ceph-deploy osd activate node1:/var/local/osd2


Once you have added your new OSD, Ceph will begin rebalancing the cluster by
migrating placement groups to your new OSD. You can observe this process with
the ``ceph`` CLI. ::

	ceph -w

You should see the placement group states change from ``active+clean`` to active
with some degraded objects, and finally ``active+clean`` when migration
completes. (Control-c to exit.)


Add a Metadata Server
---------------------

To use CephFS, you need at least one metadata server. Execute the following to
create a metadata server::

	ceph-deploy mds create {ceph-node}

For example::

	ceph-deploy mds create node1


.. note:: Currently Ceph runs in production with one metadata server only. You
   may use more, but there is currently no commercial support for a cluster
   with multiple metadata servers.


Adding Monitors
---------------

A Ceph Storage Cluster requires at least one Ceph Monitor to run. For high
availability, Ceph Storage Clusters typically run multiple Ceph
Monitors so that the failure of a single Ceph Monitor will not bring down the
Ceph Storage Cluster. Ceph uses the Paxos algorithm, which requires a majority
of monitors (i.e., 1, 2:3, 3:4, 3:5, 4:6, etc.) to form a quorum.

Add two Ceph Monitors to your cluster. ::

	ceph-deploy mon create {ceph-node}

For example::

	ceph-deploy mon create node2 node3

Once you have added your new Ceph Monitors, Ceph will begin synchronizing
the monitors and form a quorum. You can check the quorum status by executing
the following::

	ceph quorum_status --format json-pretty


.. tip:: When you run Ceph with multiple monitors, you SHOULD install and
         configure NTP on each monitor host. Ensure that the
         monitors are NTP peers.


Storing/Retrieving Object Data
==============================

To store object data in the Ceph Storage Cluster, a Ceph client must:

#. Set an object name
#. Specify a `pool`_

The Ceph Client retrieves the latest cluster map and the CRUSH algorithm
calculates how to map the object to a `placement group`_, and then calculates
how to assign the placement group to a Ceph OSD Daemon dynamically. To find the
object location, all you need is the object name and the pool name. For
example::

	ceph osd map {poolname} {object-name}

.. topic:: Exercise: Locate an Object

	As an exercise, lets create an object. Specify an object name, a path to
	a test file containing some object data and a pool name using the
	``rados put`` command on the command line. For example::

		echo {Test-data} > testfile.txt
		rados put {object-name} {file-path} --pool=data
		rados put test-object-1 testfile.txt --pool=data

	To verify that the Ceph Storage Cluster stored the object, execute
	the following::

		rados -p data ls

	Now, identify the object location::

		ceph osd map {pool-name} {object-name}
		ceph osd map data test-object-1

	Ceph should output the object's location. For example::

		osdmap e537 pool 'data' (0) object 'test-object-1' -> pg 0.d1743484 (0.4) -> up [1,0] acting [1,0]

	To remove the test object, simply delete it using the ``rados rm``
	command.	For example::

		rados rm test-object-1 --pool=data

As the cluster evolves, the object location may change dynamically. One benefit
of Ceph's dynamic rebalancing is that Ceph relieves you from having to perform
the migration manually.


.. _Preflight Checklist: ../quick-start-preflight
.. _Ceph Deploy: ../../rados/deployment
.. _ceph-deploy install -h: ../../rados/deployment/ceph-deploy-install
.. _ceph-deploy new -h: ../../rados/deployment/ceph-deploy-new
.. _ceph-deploy osd: ../../rados/deployment/ceph-deploy-osd
.. _Running Ceph with Upstart: ../../rados/operations/operating#running-ceph-with-upstart
.. _Running Ceph with sysvinit: ../../rados/operations/operating#running-ceph-with-sysvinit
.. _CRUSH Map: ../../rados/operations/crush-map
.. _pool: ../../rados/operations/pools
.. _placement group: ../../rados/operations/placement-groups
.. _Monitoring a Cluster: ../../rados/operations/monitoring
.. _Monitoring OSDs and PGs: ../../rados/operations/monitoring-osd-pg
.. _Network Configuration Reference: ../../rados/configuration/network-config-ref
.. _User Management: ../../rados/operations/user-management