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a566610aaa
Modify the examples to use the simpler syntax, not involving -- or grouping with quotes. Signed-off-by: Loic Dachary <loic-201408@dachary.org>
286 lines
9.8 KiB
ReStructuredText
286 lines
9.8 KiB
ReStructuredText
======================
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Monitoring a Cluster
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======================
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Once you have a running cluster, you may use the ``ceph`` tool to monitor your
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cluster. Monitoring a cluster typically involves checking OSD status, monitor
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status, placement group status and metadata server status.
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Interactive Mode
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================
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To run the ``ceph`` tool in interactive mode, type ``ceph`` at the command line
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with no arguments. For example::
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ceph
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ceph> health
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ceph> status
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ceph> quorum_status
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ceph> mon_status
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Checking Cluster Health
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=======================
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After you start your cluster, and before you start reading and/or
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writing data, check your cluster's health first. You can check on the
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health of your Ceph cluster with the following::
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ceph health
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If you specified non-default locations for your configuration or keyring,
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you may specify their locations::
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ceph -c /path/to/conf -k /path/to/keyring health
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Upon starting the Ceph cluster, you will likely encounter a health
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warning such as ``HEALTH_WARN XXX num placement groups stale``. Wait a few moments and check
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it again. When your cluster is ready, ``ceph health`` should return a message
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such as ``HEALTH_OK``. At that point, it is okay to begin using the cluster.
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Watching a Cluster
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==================
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To watch the cluster's ongoing events, open a new terminal. Then, enter::
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ceph -w
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Ceph will print each event. For example, a tiny Ceph cluster consisting of
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one monitor, and two OSDs may print the following::
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cluster b370a29d-9287-4ca3-ab57-3d824f65e339
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health HEALTH_OK
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monmap e1: 1 mons at {ceph1=10.0.0.8:6789/0}, election epoch 2, quorum 0 ceph1
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osdmap e63: 2 osds: 2 up, 2 in
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pgmap v41338: 952 pgs, 20 pools, 17130 MB data, 2199 objects
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115 GB used, 167 GB / 297 GB avail
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952 active+clean
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2014-06-02 15:45:21.655871 osd.0 [INF] 17.71 deep-scrub ok
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2014-06-02 15:45:47.880608 osd.1 [INF] 1.0 scrub ok
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2014-06-02 15:45:48.865375 osd.1 [INF] 1.3 scrub ok
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2014-06-02 15:45:50.866479 osd.1 [INF] 1.4 scrub ok
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2014-06-02 15:45:01.345821 mon.0 [INF] pgmap v41339: 952 pgs: 952 active+clean; 17130 MB data, 115 GB used, 167 GB / 297 GB avail
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2014-06-02 15:45:05.718640 mon.0 [INF] pgmap v41340: 952 pgs: 1 active+clean+scrubbing+deep, 951 active+clean; 17130 MB data, 115 GB used, 167 GB / 297 GB avail
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2014-06-02 15:45:53.997726 osd.1 [INF] 1.5 scrub ok
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2014-06-02 15:45:06.734270 mon.0 [INF] pgmap v41341: 952 pgs: 1 active+clean+scrubbing+deep, 951 active+clean; 17130 MB data, 115 GB used, 167 GB / 297 GB avail
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2014-06-02 15:45:15.722456 mon.0 [INF] pgmap v41342: 952 pgs: 952 active+clean; 17130 MB data, 115 GB used, 167 GB / 297 GB avail
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2014-06-02 15:46:06.836430 osd.0 [INF] 17.75 deep-scrub ok
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2014-06-02 15:45:55.720929 mon.0 [INF] pgmap v41343: 952 pgs: 1 active+clean+scrubbing+deep, 951 active+clean; 17130 MB data, 115 GB used, 167 GB / 297 GB avail
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The output provides:
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- Cluster ID
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- Cluster health status
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- The monitor map epoch and the status of the monitor quorum
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- The OSD map epoch and the status of OSDs
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- The placement group map version
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- The number of placement groups and pools
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- The *notional* amount of data stored and the number of objects stored; and,
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- The total amount of data stored.
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.. topic:: How Ceph Calculates Data Usage
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The ``used`` value reflects the *actual* amount of raw storage used. The
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``xxx GB / xxx GB`` value means the amount available (the lesser number)
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of the overall storage capacity of the cluster. The notional number reflects
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the size of the stored data before it is replicated, cloned or snapshotted.
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Therefore, the amount of data actually stored typically exceeds the notional
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amount stored, because Ceph creates replicas of the data and may also use
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storage capacity for cloning and snapshotting.
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Checking a Cluster's Usage Stats
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================================
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To check a cluster's data usage and data distribution among pools, you can
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use the ``df`` option. It is similar to Linux ``df``. Execute
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the following::
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ceph df
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The **GLOBAL** section of the output provides an overview of the amount of
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storage your cluster uses for your data.
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- **SIZE:** The overall storage capacity of the cluster.
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- **AVAIL:** The amount of free space available in the cluster.
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- **RAW USED:** The amount of raw storage used.
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- **% RAW USED:** The percentage of raw storage used. Use this number in
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conjunction with the ``full ratio`` and ``near full ratio`` to ensure that
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you are not reaching your cluster's capacity. See `Storage Capacity`_ for
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additional details.
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The **POOLS** section of the output provides a list of pools and the notional
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usage of each pool. The output from this section **DOES NOT** reflect replicas,
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clones or snapshots. For example, if you store an object with 1MB of data, the
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notional usage will be 1MB, but the actual usage may be 2MB or more depending
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on the number of replicas, clones and snapshots.
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- **NAME:** The name of the pool.
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- **ID:** The pool ID.
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- **USED:** The notional amount of data stored in kilobytes, unless the number
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appends **M** for megabytes or **G** for gigabytes.
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- **%USED:** The notional percentage of storage used per pool.
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- **Objects:** The notional number of objects stored per pool.
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.. note:: The numbers in the **POOLS** section are notional. They are not
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inclusive of the number of replicas, shapshots or clones. As a result,
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the sum of the **USED** and **%USED** amounts will not add up to the
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**RAW USED** and **%RAW USED** amounts in the **GLOBAL** section of the
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output.
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Checking a Cluster's Status
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===========================
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To check a cluster's status, execute the following::
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ceph status
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Or::
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ceph -s
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In interactive mode, type ``status`` and press **Enter**. ::
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ceph> status
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Ceph will print the cluster status. For example, a tiny Ceph cluster consisting
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of one monitor, and two OSDs may print the following::
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cluster b370a29d-9287-4ca3-ab57-3d824f65e339
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health HEALTH_OK
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monmap e1: 1 mons at {ceph1=10.0.0.8:6789/0}, election epoch 2, quorum 0 ceph1
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osdmap e63: 2 osds: 2 up, 2 in
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pgmap v41332: 952 pgs, 20 pools, 17130 MB data, 2199 objects
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115 GB used, 167 GB / 297 GB avail
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1 active+clean+scrubbing+deep
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951 active+clean
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Checking OSD Status
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===================
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You can check OSDs to ensure they are ``up`` and ``in`` by executing::
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ceph osd stat
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Or::
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ceph osd dump
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You can also check view OSDs according to their position in the CRUSH map. ::
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ceph osd tree
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Ceph will print out a CRUSH tree with a host, its OSDs, whether they are up
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and their weight. ::
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# id weight type name up/down reweight
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-1 3 pool default
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-3 3 rack mainrack
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-2 3 host osd-host
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0 1 osd.0 up 1
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1 1 osd.1 up 1
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2 1 osd.2 up 1
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For a detailed discussion, refer to `Monitoring OSDs and Placement Groups`_.
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Checking Monitor Status
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=======================
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If your cluster has multiple monitors (likely), you should check the monitor
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quorum status after you start the cluster before reading and/or writing data. A
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quorum must be present when multiple monitors are running. You should also check
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monitor status periodically to ensure that they are running.
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To see display the monitor map, execute the following::
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ceph mon stat
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Or::
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ceph mon dump
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To check the quorum status for the monitor cluster, execute the following::
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ceph quorum_status
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Ceph will return the quorum status. For example, a Ceph cluster consisting of
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three monitors may return the following:
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.. code-block:: javascript
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{ "election_epoch": 10,
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"quorum": [
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0,
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1,
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2],
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"monmap": { "epoch": 1,
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"fsid": "444b489c-4f16-4b75-83f0-cb8097468898",
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"modified": "2011-12-12 13:28:27.505520",
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"created": "2011-12-12 13:28:27.505520",
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"mons": [
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{ "rank": 0,
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"name": "a",
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"addr": "127.0.0.1:6789\/0"},
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{ "rank": 1,
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"name": "b",
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"addr": "127.0.0.1:6790\/0"},
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{ "rank": 2,
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"name": "c",
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"addr": "127.0.0.1:6791\/0"}
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]
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}
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}
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Checking MDS Status
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===================
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Metadata servers provide metadata services for Ceph FS. Metadata servers have
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two sets of states: ``up | down`` and ``active | inactive``. To ensure your
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metadata servers are ``up`` and ``active``, execute the following::
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ceph mds stat
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To display details of the metadata cluster, execute the following::
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ceph mds dump
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Checking Placement Group States
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===============================
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Placement groups map objects to OSDs. When you monitor your
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placement groups, you will want them to be ``active`` and ``clean``.
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For a detailed discussion, refer to `Monitoring OSDs and Placement Groups`_.
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.. _Monitoring OSDs and Placement Groups: ../monitoring-osd-pg
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Using the Admin Socket
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======================
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The Ceph admin socket allows you to query a daemon via a socket interface.
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By default, Ceph sockets reside under ``/var/run/ceph``. To access a daemon
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via the admin socket, login to the host running the daemon and use the
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following command::
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ceph --admin-daemon /var/run/ceph/{socket-name}
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To view the available admin socket commands, execute the following command::
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ceph --admin-daemon /var/run/ceph/{socket-name} help
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The admin socket command enables you to show and set your configuration at
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runtime. See `Viewing a Configuration at Runtime`_ for details.
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Additionally, you can set configuration values at runtime directly (i.e., the
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admin socket bypasses the monitor, unlike ``ceph tell {daemon-type}.{id}
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injectargs``, which relies on the monitor but doesn't require you to login
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directly to the host in question ).
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.. _Viewing a Configuration at Runtime: ../../configuration/ceph-conf#ceph-runtime-config
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.. _Storage Capacity: ../../configuration/mon-config-ref#storage-capacity
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