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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 07:45:52 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 07:45:52 +0000
commitcbe4cdc48486fbedede448aa59aa6a367efa1038 (patch)
tree6fc30a23fe7642fd93c5c6c702c4bc8ed5640b38 /doc/sphinx/Pacemaker_Explained/constraints.rst
parentAdding debian version 2.1.6-5. (diff)
downloadpacemaker-cbe4cdc48486fbedede448aa59aa6a367efa1038.tar.xz
pacemaker-cbe4cdc48486fbedede448aa59aa6a367efa1038.zip
Merging upstream version 2.1.7.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'doc/sphinx/Pacemaker_Explained/constraints.rst')
-rw-r--r--doc/sphinx/Pacemaker_Explained/constraints.rst65
1 files changed, 18 insertions, 47 deletions
diff --git a/doc/sphinx/Pacemaker_Explained/constraints.rst b/doc/sphinx/Pacemaker_Explained/constraints.rst
index ab34c9f..a78d6c2 100644
--- a/doc/sphinx/Pacemaker_Explained/constraints.rst
+++ b/doc/sphinx/Pacemaker_Explained/constraints.rst
@@ -7,49 +7,6 @@
Resource Constraints
--------------------
-.. index::
- single: resource; score
- single: node; score
-
-Scores
-######
-
-Scores of all kinds are integral to how the cluster works.
-Practically everything from moving a resource to deciding which
-resource to stop in a degraded cluster is achieved by manipulating
-scores in some way.
-
-Scores are calculated per resource and node. Any node with a
-negative score for a resource can't run that resource. The cluster
-places a resource on the node with the highest score for it.
-
-Infinity Math
-_____________
-
-Pacemaker implements **INFINITY** (or equivalently, **+INFINITY**) internally as a
-score of 1,000,000. Addition and subtraction with it follow these three basic
-rules:
-
-* Any value + **INFINITY** = **INFINITY**
-
-* Any value - **INFINITY** = -**INFINITY**
-
-* **INFINITY** - **INFINITY** = **-INFINITY**
-
-.. note::
-
- What if you want to use a score higher than 1,000,000? Typically this possibility
- arises when someone wants to base the score on some external metric that might
- go above 1,000,000.
-
- The short answer is you can't.
-
- The long answer is it is sometimes possible work around this limitation
- creatively. You may be able to set the score to some computed value based on
- the external metric rather than use the metric directly. For nodes, you can
- store the metric as a node attribute, and query the attribute when computing
- the score (possibly as part of a custom resource agent).
-
.. _location-constraint:
.. index::
@@ -434,6 +391,20 @@ Because the above example lets ``symmetrical`` default to TRUE, **Webserver**
must be stopped before **Database** can be stopped, and **Webserver** should be
stopped before **IP** if they both need to be stopped.
+Symmetric and asymmetric ordering
+_________________________________
+
+A mandatory symmetric ordering of "start A then start B" implies not only that
+the start actions must be ordered, but that B is not allowed to be active
+unless A is active. For example, if the ordering is added to the configuration
+when A is stopped (due to target-role, failure, etc.) and B is already active,
+then B will be stopped.
+
+By contrast, asymmetric ordering of "start A then start B" means the stops can
+occur in either order, which implies that B *can* remain active in the same
+situation.
+
+
.. index::
single: colocation
single: constraint; colocation
@@ -535,8 +506,8 @@ _____________________
| | | If ``rsc`` and ``with-rsc`` are specified, and ``rsc`` |
| | | is a :ref:`promotable clone <s-resource-promotable>`, |
| | | the constraint applies only to ``rsc`` instances in |
- | | | this role. Allowed values: ``Started``, ``Promoted``, |
- | | | ``Unpromoted``. For details, see |
+ | | | this role. Allowed values: ``Started``, ``Stopped``, |
+ | | | ``Promoted``, ``Unpromoted``. For details, see |
| | | :ref:`promotable-clone-constraints`. |
+----------------+----------------+--------------------------------------------------------+
| with-rsc-role | Started | .. index:: |
@@ -548,8 +519,8 @@ _____________________
| | | ``with-rsc`` is a |
| | | :ref:`promotable clone <s-resource-promotable>`, the |
| | | constraint applies only to ``with-rsc`` instances in |
- | | | this role. Allowed values: ``Started``, ``Promoted``, |
- | | | ``Unpromoted``. For details, see |
+ | | | this role. Allowed values: ``Started``, ``Stopped``, |
+ | | | ``Promoted``, ``Unpromoted``. For details, see |
| | | :ref:`promotable-clone-constraints`. |
+----------------+----------------+--------------------------------------------------------+
| influence | value of | .. index:: |