Tungsten Clustering

Replacing an Active Witness as a Full Cluster Node

This section explains the simple process for converting an Active Witness into a full cluster node. This process can be used to either convert the existing node or replace the witness with a new node.

First, place the cluster into MAINTENANCE mode.
```
shell> cctrl
cctrl> set policy maintenance
```
Stop the software on the existing Witness node
```
shell> stopall
```
Whether you are converting this host, or adding a new host, ensure any additional prerequisites that are needed for a full cluster node are in place, for example MySQL has been installed.
Update the ini on all nodes (including connectors) removing the witness properties and placing the new host as part of the cluster configuration, example below.
Example tungsten.ini BEFORE change
```
[defaults]
user=tungsten
home-directory=/opt/continuent
application-user=app_user
application-password=secret
application-port=3306
profile-script=~/.bash_profile
replication-user=tungsten
replication-password=secret
replication-port=13306
rest-api-admin-user=apiuser
rest-api-admin-password=secret
mysql-allow-intensive-checks=true

[nyc]
enable-active-witnesses=true
topology=clustered
master=db1
members=db1,db2,db3
witnesses=db3
connectors=db1,db2,db3
```
Show argument definitions
user=tungstenOS System User, for example tungsten. DO NOT use root.
home-directory=/opt/continuentInstallation directory.
application-user=app_userDatabase username for the connector.
application-password=secretDatabase password for the connector.
application-port=3306Port for the connector to listen on.
profile-script=~/.bash_profileAppend commands to include env.sh in this profile script.
replication-user=tungstenUser for database connection.
replication-password=secretDatabase password.
replication-port=13306Database network port.
rest-api-admin-user=apiuserSpecify the initial Admin Username for API access.Available from v7.0.0
rest-api-admin-password=secretSpecify the initial Admin User Password for API access. rest-api-admin-password alias only available from version 7.1.2 onwards.Available from v7.0.0
mysql-allow-intensive-checks=trueFor MySQL installation, enables detailed checks on the supported data types within the MySQL database to confirm compatibility.
Example tungsten.ini AFTER change
```
[defaults]
user=tungsten
home-directory=/opt/continuent
application-user=app_user
application-password=secret
application-port=3306
profile-script=~/.bash_profile
replication-user=tungsten
replication-password=secret
replication-port=13306
rest-api-admin-user=apiuser
rest-api-admin-password=secret
mysql-allow-intensive-checks=true

[nyc]
topology=clustered
master=db1
members=db1,db2,db3
connectors=db1,db2,db3
```
Show argument definitions
user=tungstenOS System User, for example tungsten. DO NOT use root.
home-directory=/opt/continuentInstallation directory.
application-user=app_userDatabase username for the connector.
application-password=secretDatabase password for the connector.
application-port=3306Port for the connector to listen on.
profile-script=~/.bash_profileAppend commands to include env.sh in this profile script.
replication-user=tungstenUser for database connection.
replication-password=secretDatabase password.
replication-port=13306Database network port.
rest-api-admin-user=apiuserSpecify the initial Admin Username for API access.Available from v7.0.0
rest-api-admin-password=secretSpecify the initial Admin User Password for API access. rest-api-admin-password alias only available from version 7.1.2 onwards.Available from v7.0.0
mysql-allow-intensive-checks=trueFor MySQL installation, enables detailed checks on the supported data types within the MySQL database to confirm compatibility.
Update the software on the existing cluster nodes and connector nodes (If separate). Include --no-connectors if you want to manually restart them when convenient.
```
shell> cd /opt/continuent/software/tungsten-clustering-8.0.4-132
shell> tools/tpm update --replace-release
```

Either install on the new host or update on the previous Witness host:

shell> cd /opt/continuent/software/tungsten-clustering-8.0.4-132
shell> tools/tpm install

or:

shell> cd /opt/continuent/software/tungsten-clustering-8.0.4-132
shell> tools/tpm update --replace-release -f

Once the software has been installed you now need to restore a backup of the database onto the node, or provision the database using the provided scripts. Either restore a backup, create and restore a new backup or use tprovision to restore the database on the host.
Start the software on the new node/old witness node
```
shell> startall
```
If you issued --no-connectors during the update, restart the connectors when convenient
```
shell> connector restart
```
Check within cctrl from one of the existing database nodes to check that the status returns the expected output, if it does, return the cluster to AUTOMATIC and the process is complete. If the output is not correct, this is usually due to metadata files not updating, therefore on every node, issue the following:
```
shell> tungsten_reset_manager
```
This will clean the metadata files and stop the manager process. Once the script has completed on all nodes, restart the manager process on each node, one-by-one, starting with the primary node first, followed by the replica:
```
shell> manager start
```
Finally, return the cluster to AUTOMATIC. If the reset process above was performed, it may take a minute or two for the ls output of cctrl to update whilst the metadata files are refreshed.