| = Activation Sequence Tools |
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| You can use the Artemis CLI to execute activation sequence maintenance/recovery tools for xref:ha.adoc#replication[Replication] with Pluggable Lock Manager. |
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| 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. |
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| Here is a disaster scenario built around the RI (using https://zookeeper.apache.org/[Apache ZooKeeper] and https://curator.apache.org/[Apache curator]) to demonstrate the usage of such commands. |
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| == ZooKeeper cluster disaster |
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| 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 manage replication? |
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| During the disaster (i.e. ZooKeeper nodes are no longer reachable) the follow occurs: |
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| * Active brokers shutdown (and if restarted, should hang waiting to reconnect to the ZooKeeper cluster again) |
| * Passive brokers unpair and wait to reconnect to the ZooKeeper cluster again |
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| Necessary administrative action: |
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| . Stop all brokers |
| . Restart ZooKeeper cluster |
| . Search for brokers with the highest local activation sequence for their `NodeID` by running this command from the `bin` folder of the broker: |
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| [,bash] |
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| $ ./artemis activation list --local |
| Local activation sequence for NodeID=7debb3d1-0d4b-11ec-9704-ae9213b68ac4: 1 |
| ---- |
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| . From the `bin` folder of the brokers with the highest local activation sequence |
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| [,bash] |
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| # 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 |
| ---- |
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| . Restart all brokers: previously active ones should be able to be active again |
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| The more ZooKeeper nodes there are the less chance that a disaster like this requires administrative intervention because it allows the ZooKeeper cluster to tolerate more failures. |
