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This document is a step by step procedure for upgrading from Scylla 4.6 to Scylla 5.0, and rollback to version 4.6 if required.
This guide covers upgrading Scylla 4.6 to Scylla 5.0 on Ubuntu 18.04. See OS Support by Platform and Version for information about supported versions.
A ScyllaDB upgrade is a rolling procedure which does not require full cluster shutdown. For each of the nodes in the cluster, you will:
Check the cluster’s schema
Drain the node and backup the data
Backup the configuration file
Stop ScyllaDB
Download and install new ScyllaDB packages
Start ScyllaDB
Validate that the upgrade was successful
Apply the following procedure serially on each node. Do not move to the next node before validating that the node you upgraded is up and running the new version.
During the rolling upgrade, it is highly recommended:
Not to use the new 5.0 features
Not to run administration functions, like repairs, refresh, rebuild or add or remove nodes. See sctool for suspending ScyllaDB Manager (only available for ScyllaDB Enterprise) scheduled or running repairs.
Not to apply schema changes
Note
Before upgrading, make sure to use the latest ScyllaDB Montioring stack.
Make sure that all nodes have the schema synced before the upgrade. The upgrade will fail if there is a schema disagreement between nodes.
nodetool describecluster
Before any major procedure, like an upgrade, it is recommended to backup all the data to an external device. In Scylla, backup is done using the nodetool snapshot command. For each node in the cluster, run the following command:
nodetool drain
nodetool snapshot
Take note of the directory name that nodetool gives you, and copy all the directories having that name under /var/lib/scylla to a backup device.
When the upgrade is completed on all nodes, remove the snapshot with the nodetool clearsnapshot -t <snapshot> command to prevent running out of space.
sudo cp -a /etc/scylla/scylla.yaml /etc/scylla/scylla.yaml.backup-src
sudo service scylla-server stop
Before upgrading, check what version you are running now using dpkg -s scylla-server. You should use the same version in case you want to rollback the upgrade. If you are not running a 4.6.x version, stop right here! This guide only covers 4.6.x to 5.0.y upgrades.
To upgrade ScyllaDB:
Update the Scylla deb repo to 5.0.
Install:
sudo apt-get clean all sudo apt-get update sudo apt-get dist-upgrade scylla
Answer ‘y’ to the first two questions.
sudo service scylla-server start
Check cluster status with nodetool status and make sure all nodes, including the one you just upgraded, are in UN status.
Use curl -X GET "http://localhost:10000/storage_service/scylla_release_version" to check the Scylla version.
Check scylla-server log (by journalctl _COMM=scylla) and /var/log/syslog to validate there are no errors.
Check again after two minutes to validate no new issues are introduced.
Once you are sure the node upgrade is successful, move to the next node in the cluster.
See Scylla Metrics Update - Scylla 4.6 to 5.0 for more information.
Note
Execute the following commands one node at the time, moving to the next node only after the rollback procedure completed successfully.
The following procedure describes a rollback from Scylla 5.0.x to 4.6.y. Apply this procedure if an upgrade from 4.6 to 5.0 failed before completing on all nodes. Use this procedure only for nodes you upgraded to 5.0.
ScyllaDB rollback is a rolling procedure which does not require full cluster shutdown. For each of the nodes you rollback to 4.6, you will:
Drain the node and stop Scylla
Retrieve the old ScyllaDB packages
Restore the configuration file
Restore system tables
Reload systemd configuration
Restart ScyllaDB
Validate the rollback success
Apply the following procedure serially on each node. Do not move to the next node before validating the node is up and running the old version.
nodetool drain
sudo service scylla-server stop
Remove the old repo file.
sudo rm -rf /etc/apt/sources.list.d/scylla.list
Update the Scylla deb repo to 4.6.
Install:
sudo apt-get update sudo apt-get remove scylla\* -y sudo apt-get install scylla
Answer ‘y’ to the first two questions.
sudo rm -rf /etc/scylla/scylla.yaml
sudo cp -a /etc/scylla/scylla.yaml.backup-src | /etc/scylla/scylla.yaml
Restore all tables of system and system_schema from the previous snapshot because 5.0 uses a different set of system tables. See Restore from a Backup and Incremental Backup for reference.
cd /var/lib/scylla/data/keyspace_name/table_name-UUID/snapshots/<snapshot_name>/
sudo cp -r * /var/lib/scylla/data/keyspace_name/table_name-UUID/
sudo chown -R scylla:scylla /var/lib/scylla/data/keyspace_name/table_name-UUID/
It is required to reload the unit file if the systemd unit file is changed.
sudo systemctl daemon-reload
sudo service scylla-server start
Check the upgrade instructions above for validation. Once you are sure the node rollback is successful, move to the next node in the cluster.