Upgrade Guide - Scylla 1.7 to 2.0 for Red Hat Enterprise 7 or CentOS 7

This document is a step by step procedure for upgrading from Scylla 1.7 to Scylla 2.0, and rollback to 1.7 if required.

Applicable versions

This guide covers upgrading Scylla from the following versions: 1.7.x (x >= 4) to Scylla version 2.0.y, on the following platforms:

  • Red Hat Enterprise Linux, version 7 and later
  • CentOS, version 7 and later
  • No longer provide packages for Fedora

Upgrade Procedure

A Scylla upgrade is a rolling procedure which does not require full cluster shutdown. For each of the nodes in the cluster, serially (i.e. one at a time), you will:

  • check cluster schema
  • drain node and backup the data
  • backup configuration file
  • stop Scylla
  • download and install new Scylla 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 2.0 features
  • Not to run administration functions, like repairs, refresh, rebuild or add or remove nodes
  • Not to apply schema changes

Check cluster schema

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

Drain node and backup the data

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.

Upgrade steps

Backup configuration file

sudo cp -a /etc/scylla/scylla.yaml /etc/scylla/scylla.yaml.backup-1.7

Stop Scylla

sudo systemctl stop scylla-server

Download and install the new release

Before upgrading, check what version you are running now using rpm -qa | grep scylla-server. You should use the same version in case you want to rollback the upgrade. If you are not running a 1.7.x version, stop right here! This guide only covers 1.7.x to 2.0.y upgrades.

To upgrade:

  1. Update the Scylla RPM repo to 2.0
  2. install
sudo yum update scylla\* -y

Start the node

sudo systemctl start scylla-server

Validate

  1. Check cluster status with nodetool status and make sure all nodes, including the one you just upgraded, are in UN status.
  2. Use curl -X GET "http://localhost:10000/storage_service/scylla_release_version" to check scylla version.
  3. Use journalctl _COMM=scylla to check there are no new errors in the log.
  4. 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.

Rollback Procedure

The following procedure describes a rollback from Scylla release 2.0.x to 1.7.y (y >= 4). Apply this procedure if an upgrade from 1.7 to 2.0 failed before completing on all nodes. Use this procedure only for nodes you upgraded to 2.0

Scylla rollback is a rolling procedure which does not require full cluster shutdown. For each of the nodes rollback to 1.7, you will:

  • drain the node and stop Scylla
  • retrieve the old Scylla packages
  • restore the configuration file
  • 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.

Rollback steps

Gracefully shutdown Scylla

nodetool drain
sudo systemctl stop scylla-server

Download and install the new release

  1. Remove the old repo file.
sudo rm -rf /etc/yum.repos.d/scylla.repo
  1. Update the Scylla RPM repo to 1.7
  2. Install
sudo yum clean all
sudo yum remove scylla-tools-core
sudo yum downgrade scylla\* -y
sudo yum install scylla

Restore the configuration file

sudo rm -rf /etc/scylla/scylla.yaml
sudo cp -a /etc/scylla/scylla.yaml.backup-1.7 /etc/scylla/scylla.yaml

Restore system tables

Restore all tables of system and system_schema from previous snapshot, 2.0 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/

Start the node

sudo systemctl start scylla-server

Validate

Check upgrade instruction above for validation. Once you are sure the node rollback is successful, move to the next node in the cluster.