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author | Zac Dover <zac.dover@proton.me> | 2023-06-10 04:08:41 +0200 |
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committer | Zac Dover <zac.dover@proton.me> | 2023-06-10 14:20:02 +0200 |
commit | dc93181f04f772b53f0c86a34ef43a14bfba6ef8 (patch) | |
tree | 59151cd5f61976c2a0ff094474ba16cc3ae2202c | |
parent | Merge pull request #51988 from ljflores/wip-release-checklist (diff) | |
download | ceph-dc93181f04f772b53f0c86a34ef43a14bfba6ef8.tar.xz ceph-dc93181f04f772b53f0c86a34ef43a14bfba6ef8.zip |
doc/rados: edit change-mon-elections
Edit doc/rados/operations/change-mon-elections.rst.
https://tracker.ceph.com/issues/58485
Co-authored-by: Anthony D'Atri <anthony.datri@gmail.com>
Signed-off-by: Zac Dover <zac.dover@proton.me>
-rw-r--r-- | doc/rados/operations/change-mon-elections.rst | 104 |
1 files changed, 58 insertions, 46 deletions
diff --git a/doc/rados/operations/change-mon-elections.rst b/doc/rados/operations/change-mon-elections.rst index 9521850a121..7418ea3633d 100644 --- a/doc/rados/operations/change-mon-elections.rst +++ b/doc/rados/operations/change-mon-elections.rst @@ -1,88 +1,100 @@ .. _changing_monitor_elections: -===================================== -Configure Monitor Election Strategies -===================================== +======================================= +Configuring Monitor Election Strategies +======================================= -By default, the monitors will use the ``classic`` mode. We -recommend that you stay in this mode unless you have a very specific reason. +By default, the monitors are in ``classic`` mode. We recommend staying in this +mode unless you have a very specific reason. -If you want to switch modes BEFORE constructing the cluster, change -the ``mon election default strategy`` option. This option is an integer value: +If you want to switch modes BEFORE constructing the cluster, change the ``mon +election default strategy`` option. This option takes an integer value: -* 1 for "classic" -* 2 for "disallow" -* 3 for "connectivity" +* ``1`` for ``classic`` +* ``2`` for ``disallow`` +* ``3`` for ``connectivity`` -Once your cluster is running, you can change strategies by running :: +After your cluster has started running, you can change strategies by running a +command of the following form: $ ceph mon set election_strategy {classic|disallow|connectivity} Choosing a mode =============== -The modes other than classic provide different features. We recommend -you stay in classic mode if you don't need the extra features as it is -the simplest mode. -The disallow Mode -================= -This mode lets you mark monitors as disallowed, in which case they will -participate in the quorum and serve clients, but cannot be elected leader. You -may wish to use this if you have some monitors which are known to be far away -from clients. -You can disallow a leader by running: +The modes other than ``classic`` provide specific features. We recommend staying +in ``classic`` mode if you don't need these extra features because it is the +simplest mode. + +.. _rados_operations_disallow_mode: + +Disallow Mode +============= + +The ``disallow`` mode allows you to mark monitors as disallowed. Disallowed +monitors participate in the quorum and serve clients, but cannot be elected +leader. You might want to use this mode for monitors that are far away from +clients. + +To disallow a monitor from being elected leader, run a command of the following +form: .. prompt:: bash $ ceph mon add disallowed_leader {name} -You can remove a monitor from the disallowed list, and allow it to become -a leader again, by running: +To remove a monitor from the disallowed list and allow it to be elected leader, +run a command of the following form: .. prompt:: bash $ ceph mon rm disallowed_leader {name} -The list of disallowed_leaders is included when you run: +To see the list of disallowed leaders, examine the output of the following +command: .. prompt:: bash $ ceph mon dump -The connectivity Mode -===================== -This mode evaluates connection scores provided by each monitor for its -peers and elects the monitor with the highest score. This mode is designed -to handle network partitioning or *net-splits*, which may happen if your cluster -is stretched across multiple data centers or otherwise has a non-uniform -or unbalanced network topology. +Connectivity Mode +================= + +The ``connectivity`` mode evaluates connection scores that are provided by each +monitor for its peers and elects the monitor with the highest score. This mode +is designed to handle network partitioning (also called *net-splits*): network +partitioning might occur if your cluster is stretched across multiple data +centers or otherwise has a non-uniform or unbalanced network topology. -This mode also supports disallowing monitors from being the leader -using the same commands as above in disallow. +The ``connectivity`` mode also supports disallowing monitors from being elected +leader by using the same commands that were presented in :ref:`Disallow Mode <rados_operations_disallow_mode>`. Examining connectivity scores ============================= -The monitors maintain connection scores even if they aren't in -the connectivity election mode. You can examine the scores a monitor -has by running: + +The monitors maintain connection scores even if they aren't in ``connectivity`` +mode. To examine a specific monitor's connection scores, run a command of the +following form: .. prompt:: bash $ ceph daemon mon.{name} connection scores dump -Scores for individual connections range from 0-1 inclusive, and also -include whether the connection is considered alive or dead (determined by -whether it returned its latest ping within the timeout). +Scores for an individual connection range from ``0`` to ``1`` inclusive and +include whether the connection is considered alive or dead (as determined by +whether it returned its latest ping before timeout). -While this would be an unexpected occurrence, if for some reason you experience -problems and troubleshooting makes you think your scores have become invalid, -you can forget history and reset them by running: +Connectivity scores are expected to remain valid. However, if during +troubleshooting you determine that these scores have for some reason become +invalid, drop the history and reset the scores by running a command of the +following form: .. prompt:: bash $ ceph daemon mon.{name} connection scores reset -While resetting scores has low risk (monitors will still quickly determine -if a connection is alive or dead, and trend back to the previous scores if they -were accurate!), it should also not be needed and is not recommended unless -requested by your support team or a developer. +Resetting connectivity scores carries little risk: monitors will still quickly +determine whether a connection is alive or dead and trend back to the previous +scores if those scores were accurate. Nevertheless, resetting scores ought to +be unnecessary and it is not recommended unless advised by your support team +or by a developer. |