Every high availability group has to have an associated
policy. This policy determines which members of a high availability
group to put in the active state.
Before you begin
Before creating a new policy, you should review the following
topics:
You should also know:
- The name of the core group that you want to associate with the
new policy.
- The name of the high availability group that you want this policy
to control.
- The function, such as transaction log recovery or messaging engine,
that is associated with this high availability group.
- The policy types, such as One of N or Static, that this function
supports.
- The type of policy you want to create.
- The policy settings, such as failback, and preferred servers only,
that you want to configure for this policy.
About this task
The product includes default policies that are already associated
with the high availability groups some of the product components use.
If these default policies do not meet the requirements of your installation,
it is recommended that you create a new policy instead of changing
one of the default policies. The creation of new policies provides
you with the capability to tailor the policy settings to your installations
requirements while giving you the option to revert back to the default
policy.
Procedure
- In the administrative console, click core_group_name > Policies
> New.
- Select the new policy you want in effect for a specific
high availability group.
If you need to define a new policy,
the policy options are:
- All active policy: All of the group members are activated.
- M of N policy: M group members are activated. The number
that is represented by M is defined as part of the policy details.
- No operation policy: No group members are activated.
- One of N policy: Only one group member is activated.
- Static policy: The active members of a group are statically configured.
For messaging engines in service integration, only the Static,
One of N, and No operation policies apply.
- Click Next.
- Specify a name for the policy in the Name field. The name
must be unique within the scope of the core group.
Make
the name meaningful to other administrators.
- Optional: Specify a Description of the policy
in the description field.
This description might include
the name of the associated core group.
- Specify a value for the Is alive timer field, if the default
value is too long or too short a time period.
This value
determines how frequently the high availability manager checks the
health of the high availability group members. The default value is
0 seconds.
- If you specify -1 (minus 1), the Is alive
timer is disabled.
- If you specify 0 (zero), the value that is
specified for the Is alive timer at the core group services level
is used for high availability groups that are associated with this
policy.
- If you specify an integer between 1 and 2147483647, inclusive,
this value is used for the high availability groups that are associated
with this policy.
- Make sure the Quorum field is not selected.
You should not enable Quorum unless you are explicitly instructed
to do so in the documentation for some other product.
- Select the Failback field if you
want to have the high availability manager make the most preferred
member the currently active member whenever this action is possible.
This option is available only for M of N and One of N policies.
- Select the Preferred servers only field if you want the high availability manager to only activate
group members on servers that are contained in the Preferred servers
list.
This option is available only for M of N and One
of N policies. If you select this option, you must configure a list
of preferred servers. A description of how to set up this list is
provided in a later optional step.
- Specify the number of group members that you want active
in the Number of active members field.
This option is available
only for an M of N policy.
- Click Apply and then select Match criteria.
- On the next panel, click New and
then configure the match criterion for this policy.
- In the Name field, specify the name of one of the name-value
pairs contained in the name of the high availability group that you
want to associate with this policy.
For more information
about high availability group names, see High availability groups.
- In the Value field, specify the value of the name-value
pair you specified in the Name field.
- Optional: In the Description field, add
a description of this match criterion.
For example, you
might specify First attribute to indicate that
this name-value pair matches the first attribute contained in the
group name.
- Click OK.
- Repeat these steps for each additional attribute you
want to include as part of your match criterion.
You should set the match criterion for a new policy to two or
more of the name-value attributes that are contained in the name of
the high availability group to ensure that this policy is used instead
of one of the product default policies.
- In the Additional Properties section, select the Static group servers field to configure the list of servers
that you want activated.
This option is available only
for Static policies. Click Add to move core
group servers into the list of Static group servers, and then Click OK after you complete the list.
- Optional: Under Additional Properties, select Preferred servers and select the preferred servers for
this policy.
This option is available only if you selected
the Preferred servers only field for M of N and One of N policies.
If you do not set up this list, no group members are activated.
Click Add to move core group servers into
the list of preferred servers.
Select specific servers in the
list and click Move up and Move
down to adjust the order of the servers within the list.
Make sure that the most preferred server is at the beginning of the
list and the least preferred server is at the end of the list.
After you complete the preferred servers list, click OK.
Important: Use caution when selecting
preferred servers. The product cannot detect if you select an inappropriate
server as a preferred server. For example, if the policy affects a
messaging engine or transaction service, only select preferred servers
from the messaging engine cluster. Similarly, if the policy affects
a transaction service, only select preferred servers from the transaction
service cluster.
- Click OK and then click Review.
- Select Synchronize changes with nodes, and then click Save.
Results
The new policy goes into effect after it is saved and synchronized.
You do not have to stop and restart the affected application servers.
What to do next
You can change the Failback and Preferred servers only options for this policy without
stopping and restarting the affected application servers.You can
create or update the list of preferred servers that for this policy
without stopping and restarting the affected application servers.