Core group policy settings

Use this page to define a policy for a high availability group. Even though a policy is defined at the core group level, it only applies to a high availability group that is contained within the core group.

To view this administrative console page, click Servers > Core groups > Core group settings > New or existing core group > Policies > policy_name.

Name Name of the policy. This name must be unique within the scope of a core group.
Policy type Specifies the policy type that was selected when this policy was created. This is a read-only field. If you want to change the policy type, delete this policy and then create it again specifying a different policy type. If this is an IBM provided policy, do not delete it. Instead create a new policy and specify more of the attributes contained in the high availability group's name as the match criterion for this new policy. The policy with the greatest number of matches to attributes in a group's name is the policy that is associated with that group.
Description Use this field to provide meaningful information about this policy. For example, the Clustered TM Policy provided with the product has TM One-Of-N Policy in the description field.
Is alive timer The interval of time at which the high availability manager will check the health of the active group members that are governed by this policy. If a group member has failed, the server on which the group member resides is restarted.

Data type Integer

  • Valid values are -1 to 600 seconds, inclusive.

  • If -1 (negative 1) is specified, this function is disabled.

  • If 0 (zero) is specified, the frequency at which the high availability manager checks the health of the active group members is determined by the time interval specified at the application server process level.

  • If a value larger than 0 (zero) is specified, the high availability manager uses the time interval specified here, instead of the one specified at the application server process level, when determining how frequently it should check the health of the high availability group members using this policy.

Default 0 (zero)
Quorum When selected, quorum checking is enabled for a group governed by this policy. Quorum is a mechanism that can be used to protect resources that are shared across members of the group in the event of a failure. CAUTION: Quorum is an advanced hardware function and should not be enabled unless you thoroughly understand how to properly use this function. If not used properly, this function can cause data corruption.

The Quorum setting in the policy will only have an effect if the following items are true:

  • The group members are also cluster members.

  • GroupName.WAS_CLUSTER=clustername must be specified as a property in the group name of any high availability group matching this policy.

When enabled, any group using this policy will not achieve quorum until a majority of the members are running. For example, if there are n members in the group, (n/2) + 1 servers must be online in order to achieve quorum. No group members will be activated until quorum has been achieved.

The quorum mechanism is designed to work in conjunction with a hardware control facility that allows application servers to be shut down if a failure causes the group to be partitioned.

Fail back When selected, if a failure occurs, work items assigned to the failing server are moved to the server that is designated as the most preferred server for the group. This field only applies for M of N and One of N policies.
Preferred servers only When selected, group members are only activated on servers that are on the list of preferred servers for this group. This field only applies for M of N and One of N policies.
Number of active members This field only applies for the M of N policy. Use this field to specify how many of the high availability group members are to be activated.

The options available under Additional Properties are determined by the type of policy selected. One or more of the following options are available:

Custom properties Use this link to specify custom properties for the policy.
Match criteria Use this link to set up a match criterion for the policy.
Preferred servers Use this link to set up a list of servers that are given preference when group members are activated.
Static group servers Use this link to set up a list of the specific servers that are activated.

 


 

 

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