IBM SG24-5131-00 User Manual
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IBM Certification Study Guide AIX HACMP
8.5.3.1 Resource Migration Types
Before performing a resource migration, decide if you will declare the
migration
Before performing a resource migration, decide if you will declare the
migration
sticky
or
non-sticky
.
Sticky Resource Migration
A sticky migration permanently attaches a resource group to a specified
node. The resource group attempts to remain on the specified node during a
node failover or reintegration.
A sticky migration permanently attaches a resource group to a specified
node. The resource group attempts to remain on the specified node during a
node failover or reintegration.
Since stickiness is a behavioral property of a resource group, assigning a
node as a sticky location makes the specified resource group a sticky
resource. Older sticky locations are superseded only by new sticky migration
requests for the same resource group, or they are removed entirely during
non-sticky migration requests for the same resource group. If it is not
possible to place a resource group on its sticky location (because that node is
down), the normal resource policy is invoked, allowing the resource to
migrate according to the takeover priority specified in the resource group’s
node list.
node as a sticky location makes the specified resource group a sticky
resource. Older sticky locations are superseded only by new sticky migration
requests for the same resource group, or they are removed entirely during
non-sticky migration requests for the same resource group. If it is not
possible to place a resource group on its sticky location (because that node is
down), the normal resource policy is invoked, allowing the resource to
migrate according to the takeover priority specified in the resource group’s
node list.
For both cascading and rotating resource groups, a normal resource policy
means that other cluster nodes in the group’s node list are consulted at the
time the sticky location fails to find the highest-priority node active. After
finding the active node, cascading resource groups will continually migrate to
the highest-priority node in the group’s node list (ultimately residing at the
sticky location). Rotating resource groups stay put until the sticky location
returns to the cluster.
means that other cluster nodes in the group’s node list are consulted at the
time the sticky location fails to find the highest-priority node active. After
finding the active node, cascading resource groups will continually migrate to
the highest-priority node in the group’s node list (ultimately residing at the
sticky location). Rotating resource groups stay put until the sticky location
returns to the cluster.
You can attach the optional keyword
sticky
to any migration you perform,
regardless of the resource group configuration (rotating or cascading).
However, with very few exceptions, you always use the sticky location for
cascading configurations, and do not use it for rotating configurations.
However, with very few exceptions, you always use the sticky location for
cascading configurations, and do not use it for rotating configurations.
Non-Sticky Resource Migration
Resource groups on nodes not designated sticky are by default transient,
non-sticky resources. These resources are temporarily placed on the
specified node with the highest priority in the node list until the next failover or
reintegration occurs. Non-sticky resources are best suited for use with
rotating resource group configurations because of this transient behavior.
Resource groups on nodes not designated sticky are by default transient,
non-sticky resources. These resources are temporarily placed on the
specified node with the highest priority in the node list until the next failover or
reintegration occurs. Non-sticky resources are best suited for use with
rotating resource group configurations because of this transient behavior.
Because the normal behavior of cascading resources is to bound back to the
highest available node in their node list, non-sticky migrations are usually not
the best choice. The one instance in which a non-sticky migration of a
cascading resource might make sense is if this resource has the
highest available node in their node list, non-sticky migrations are usually not
the best choice. The one instance in which a non-sticky migration of a
cascading resource might make sense is if this resource has the