dscontrol highavailability

You can control high availability functions with the dscontrol highavailability command.

Syntax

Parameters

backup

Specify information for either the primary or backup machine.

add
Defines and runs the high availability functions for this machine.
- primary
  Identifies the Dispatcher machine that has a primary role.
- backup
  Identifies the Dispatcher machine that has a backup role.
- auto
  Specifies an automatic recovery strategy, in which the primary machine will resume routing packets as soon as it comes back into service.
- manual
  Specifies a manual recovery strategy, in which the primary machine does not resume routing packets until the administrator issues a takeover command.
- port
  An unused UDP port on both machines, to be used by Dispatcher for its heartbeat messages. The port must be the same for both the primary and backup machines.
delete
Removes this machine from high availability, so that it will no longer be used as a backup or primary machine.

heartbeat

Defines a communication session between the primary and backup Dispatcher machines.

add
Tell the source Dispatcher the address of its partner (destination address).
- source_address
  Source address. The IP address or hostname of this Dispatcher machine.
- destination_address
  Destination address. The IP address or hostname of the other Dispatcher machine.
The source_address and destination_address must be the NFAs of the machines for at least one heartbeat pair.
delete address
Removes the specified heartbeat information. You can specify either the source_address or destination_address of the heartbeat pair.

reach

Add or delete an address for the Dispatchers to monitor. Reach targets are optional and not required for high availability. The reach target can be defined as any device that is critical for Load Balancer to communicate with clients. Both Dispatchers must define the same target.

add address
Adds a target address for the reach advisor. The address field is the IP address or hostname of the target node.
delete address
Removes a target address from the reach advisor. The address field is the IP address or hostname of the target node.

Avoid trouble: If reach targets are defined, the manager must be running to monitor the status of reach targets.

status

Return a report on high availability. Machines are identified as having one of three status conditions or states:

Active: A given machine (either a primary, backup, or both) is routing packets.
Standby: A given machine (either a primary, backup, or both) is not routing packets; it is monitoring the state of an active Dispatcher.
Idle: A given machine is routing packets, and is not trying to establish contact with its partner Dispatcher.

takeover

Takeover forces the standby Dispatcher to become active and to begin routing packets. The takeover command is only accepted when the high availability strategy is manual and the Dispatcher is in the standby state.

Note:

The high availability roles of the Dispatchers (primary and backup) do not change. Only their current high availability state (active or standby) changes.
There are three possible takeover scripts, goActive, goStandby, and goInOp. These scripts can be customized. For more information about these scripts, see Scripts to run with high availability.

Samples

To check the high availability status of a machine:
```
dscontrol highavailability status
```
To add the backup information to the primary machine using the automatic recovery strategy and port 80:
```
dscontrol highavailability backup add primary auto 80
```
To add an address that the Dispatcher must be able to reach:
```
dscontrol highavailability reach add 9.67.125.18
```

To add heartbeat information for the primary and backup machines

Primary Dispatcher:

dscontrol highavailability heartbeat add 9.67.111.3 9.67.186.8

Backup Dispatcher:

dscontrol highavailability heartbeat add 9.67.186.8 9.67.111.3

To tell the standby Dispatcher to become active, forcing the active machine to become standby:
```
dscontrol highavailability takeover
```