Upgrading Cassandra

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To prepare for Cassandra upgrade

Ensure that all Cassandra nodes are ready. Run the following command and verify that all nodes are Up and Normal:
```
nodetool status
```
Leave the Cassandra service running but stop all Teamwork Cloud services.
Back up your current database before upgrading.
Upgrade all Cassandra data tables to current version by running the following command:
```
nodetool upgradesstables
```
This process can take a long time for large databases. To run the upgrade process in the background, you can use the Linux nohup command:
nohup nodetool upgradesstables &
Make sure this process is completed before proceeding!

To upgrade Cassandra

IMPORTANT! Flush memtables to the disk by executing the following command:
```
nodetool drain
```
Stop the Cassandra service.
Backup the Cassandra configuration file at: /etc/cassandra/default.conf/cassandra.yaml
Make a note of the existing cluster name and token count with the following command:
```
grep -E 'num_tokens:|cluster_name:' cassandra.yaml
```
Uninstall/remove Cassandra (example with yum package manager)
```
sudo yum remove -y cassandra
```
Install new version of Cassandra (for installation instructions, see Installing Cassandra on Linux or Installing Cassandra on Windows).
Check the cluster name and token count in cassandra.yaml. If needed, replace the default values with the values set in the previous version. The example below shows the default values for a Cassandra installation.
Example
```
cluster_name: 'Test Cluster'
num_tokens: 16
```
Cassandra 4 Configuration
The cluster name and token count must match those values set in the previous version of Cassandra.
Start the Cassandra service.
Check if the service is running smoothly:
- Check the log file for startup errors.
- Verify that all nodes have a status of Up and Normal with this command:
```
nodetool status
```

Additional resources