# Activation Sequence Tools

You can use the Artemis CLI to execute activation sequence maintenance/recovery tools for Pluggable Quorum Replication.

The 2 main commands are `activation list` and `activation set`, that can be used together to recover some disaster happened to local/coordinated activation sequences.

Here is a disaster scenario built around the RI (using Apache Zookeeper and Apache curator) to demonstrate the usage of such commands.

## Troubleshooting Case: Zookeeper Cluster disaster

A proper Zookeeper cluster should use at least 3 nodes, but what happens if all these nodes crash loosing any activation state information required to run an Artemis replication cluster?

During the disaster ie Zookeeper nodes no longer reachable, brokers:

- live ones shutdown (and if restarted by a script, should hang awaiting to connect to the Zookeeper cluster again)
- replicas become passive, awaiting to connect to the Zookeeper cluster again

Admin should:

1. stop all Artemis brokers
2. restart Zookeeper cluster
3. search brokers with the highest local activation sequence for their `NodeID`, by running this command from the `bin` folder of the broker:

    $ ./artemis activation list --local
    Local activation sequence for NodeID=7debb3d1-0d4b-11ec-9704-ae9213b68ac4: 1

1. from the `bin` folder of the brokers with the highest local activation sequence

    # assuming 1 to be the highest local activation sequence obtained at the previous step
    # for NodeID 7debb3d1-0d4b-11ec-9704-ae9213b68ac4
    $ ./artemis activation set --remote --to 1
    Forced coordinated activation sequence for NodeID=7debb3d1-0d4b-11ec-9704-ae9213b68ac4 from 0 to 1

1. restart all brokers: previously live ones should be able to be live again

The higher the number of Zookeeper nodes are, the less the chance are that a disaster like this requires Admin intervention, because it allows the Zookeeper cluster to tolerate more failures.

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