Enabling AdaptiveHA for a service group


Enabling AdaptiveHA for a service group
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AdaptiveHA enables VCS to make dynamic decisions about failing over an application to the biggest available system.

To enable AdaptiveHA for a service group

Ensure cluster attribute Statistics is set to Enabled. You can check by using the following command,
# haclus -display|grep Statistics

You cannot edit this value at run time.
Set the Load of the service group in terms of CPU, Memory, or Swap in absolute units. The unit can be of any following values:
- CPU, MHz, or GHz for CPU
- GB or MB for Memory
- GB or MB for Swap
Define at least one key for the Load attribute.
Check the default value of the MeterWeight attribute at the cluster level. If the attribute does not meet the service group's meter weight requirement, then set the MeterWeight at the service group level.
Set or edit the values for the following service group attributes in main.cf:
- Modify the values of Load and MeterWeight as decided in the preceding steps.
- Set the value of FailOverPolicy to BiggestAvailable.
  
  You can set or edit the service group level attributes Load, MeterWeight, and FailOverPolicy during run time.

After you complete the above steps, AdaptiveHA is enabled. The service group follows the BiggestAvailable policy during a failover.

The following table provides information on various attributes and the values they can take to enable AdaptiveHA:

Table:

Use-case	Attribute values to be set
To turn on host metering	Set the cluster attribute Statistics to MeterHostOnly.
To turn off host metering	Set the cluster attribute Statistics to Disabled.
To turn on host metering and forecasting	Set the cluster attribute Statistics to Enabled.
To enable hagrp -forecast CLI option	Set the cluster attribute Statistics to Enabled and also set the service group attribute Load based on your application's CPU, Mem or Swap usage.
To check the meters supported for any host or cluster node	Verify the value of cluster attribute HostAvailableMeters.
To enable host metering, forecast, and policy decisions using forecast	Perform the following actions: Set the cluster attribute Statistics to Enabled Set the service group attribute FailOverPolicy to BiggestAvailable. Set service group attribute Load based on your application's CPU, Mem or Swap usage. Optionally, set the service group attribute MeterWeight.
To change metering or forecast frequency	Set the MeterInterval and ForecastCycle keys in the cluster attribute MeterControl accordingly.
To check the available capacity and its forecast	Use the following commands to check values for available capacity and its forecast: *# hasys -value system_name* AvailableCapacity # hasys -value system_name HostAvailableForecast**
To check if the metering and forecast is up-to-date	The metering value is up-to-date when the difference between GlobalCounter and AvailableGC is less than or equal to 24. The forecasting value is up-to-date when the difference between GlobalCounter and AvailableGC is less than or equal to 72.

See Cluster attributes.

See Service group attributes.

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