第 11 章 Determining which nodes a resource can run on

Procedure

• The following command creates a location constraint for a resource to prefer the specified node or nodes. Note that it is possible to create constraints on a particular resource for more than one node with a single command:

  # pcs constraint location rsc prefers node[=score] [node[=score]] ...

• The following command creates a location constraint for a resource to avoid the specified node or nodes:

  # pcs constraint location rsc avoids node[=score] [node[=score]] ...

• The following table summarizes the meanings of the basic options for configuring location constraints:

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  表 11.1. Location Constraint Options

  Field	Description
  rsc	A resource name
  node	A node’s name
  score	Positive integer value to indicate the degree of preference for whether the given resource should prefer or avoid the given node. INFINITY is the default score value for a resource location constraint. A value of INFINITY for score in a pcs constraint location rsc prefers command indicates that the resource will prefer that node if the node is available, but does not prevent the resource from running on another node if the specified node is unavailable. A value of INFINITY for score in a pcs constraint location rsc avoids command indicates that the resource will never run on that node, even if no other node is available. This is the equivalent of setting a pcs constraint location add command with a score of -INFINITY. A numeric score (that is, not INFINITY) means the constraint is optional, and will be honored unless some other factor outweighs it. For example, if the resource is already placed on a different node, and its resource-stickiness score is higher than a prefers location constraint’s score, then the resource will be left where it is.

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Procedure

• The following command creates a location constraint to specify that resources dummy0 to dummy9 prefer node1:

  # pcs constraint location 'regexp%dummy[0-9]' prefers node1

Procedure

• To configure a location constraint with extended regular expressions:

  # pcs constraint location 'regexp%dummy[[:digit:]]' prefers node1

• If resources is specified, location constraints are displayed per resource. This is the default behavior.
• If nodes is specified, location constraints are displayed per node.
• If specific resources or nodes are specified, then only information about those resources or nodes is displayed.

Procedure

• To list all current location constraints:

  # pcs constraint location [config [resources [resource...]] | [nodes [node...]]] [--full]

• To display all current location, order, and colocation constraints, use the following command. To show the internal constraint IDS, specify the --full option:

  # pcs constraint [config] [--full]

  By default, listing resource constraints does not display expired constraints. To include expired constraints in the listing, use the --all option of the pcs constraint command. This will list expired constraints, noting the constraints and their associated rules as (expired) in the display.

• To list the constraints that reference specific resources:

  # pcs constraint ref resource ...