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This document is a step by step procedure for upgrading from Scylla 4.5 to Scylla 4.6, and rollback to 4.5 if required.
This guide covers upgrading Scylla from the following versions: 4.5.x or later to Scylla version 4.6.y on the following platform:
Debian 9
A Scylla upgrade is a rolling procedure which does not require full cluster shutdown. For each of the nodes in the cluster, you will:
Check cluster schema
Drain node and backup the data
Backup configuration file
Stop Scylla
Download and install new Scylla packages
Optional: update 3rd party and OS packages
Start Scylla
Validate that the upgrade was successful
Apply the following procedure serially on each node. Do not move to the next node before validating the node is up and running with the new version.
During the rolling upgrade it is highly recommended:
Not to use new 4.6 features
Not to run administration functions, like repairs, refresh, rebuild or add or remove nodes. See sctool for suspending Scylla Manager (only available Scylla Enterprise) scheduled or running repairs.
Not to apply schema changes
Note
Before upgrading, make sure to use the latest Scylla Montioring stack.
Make sure that all nodes have the schema synched prior to upgrade, we won’t survive an upgrade that has 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 this name under /var/lib/scylla to a backup device.
When the upgrade is complete (all nodes), the snapshot should be removed by nodetool clearsnapshot -t <snapshot>, or you risk 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 4.5.x version, stop right here! This guide only covers 4.5.x to 4.6.y upgrades.
To upgrade:
Update the Scylla deb repo to 4.6
Install
sudo apt-get clean all sudo apt-get update sudo apt-get dist-upgrade scylla
Answer ‘y’ to the first two questions.
Note
Alternator users upgrading from Scylla 4.0 to 4.1, need to set default isolation level
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 scylla version.
Check scylla-server log (by journalctl _COMM=scylla) and /var/log/syslog to validate there are no errors.
Check again after 2 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.
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 release 4.6.x to 4.5.y. Apply this procedure if an upgrade from 4.5 to 4.6 failed before completing on all nodes. Use this procedure only for nodes you upgraded to 4.6
Scylla rollback is a rolling procedure which does not require full cluster shutdown. For each of the nodes rollback to 4.5, you will:
Drain the node and stop Scylla
Retrieve the old Scylla packages
Restore the configuration file
Restore system tables
Reload systemd configuration
Restart Scylla
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 with the new 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 4.5
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 previous snapshot, 4.6 uses a different set of system tables. Reference doc: Restore from a Backup and Incremental Backup
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/
Require to reload the unit file if the systemd unit file is changed.
sudo systemctl daemon-reload
sudo service scylla-server start
Check upgrade instruction above for validation. Once you are sure the node rollback is successful, move to the next node in the cluster.