Traffic encryption is enabled by default¶

The pxc_encrypt_cluster_traffic variable, which enables traffic encryption, is set to ON by default in Percona XtraDB Cluster 8.0.

Unless you configure a node accordingly (each node in your cluster must use the same SSL certificates) or try to join a cluster running Percona XtraDB Cluster 5.7 which unencrypted cluster traffic, the node will not be able to join resulting in an error.

... [ERROR] ... [Galera] handshake with remote endpoint ...
This error is often caused by SSL issues. ...

Not recommended to mix Percona XtraDB Cluster 5.7 nodes with Percona XtraDB Cluster 8.0 nodes¶

Shut down the cluster and upgrade each node to Percona XtraDB Cluster 8.0. It is important that you make backups before attempting an upgrade.

PXC Strict Mode is enabled by default¶

Percona XtraDB Cluster in 8.0 runs with PXC Strict Mode enabled by default. This will deny any unsupported operations and may halt the server if a strict mode validation fails. It is recommended to first start the node with the pxc_strict_mode variable set to PERMISSIVE in the MySQL configuration file (on Debian and Ubuntu /etc/mysql/mysql.conf.d/mysqld.cnf; on CentOS and Red Hat /etc/my.cnf).

After you check the log for any tech preview features or unsupported features and you have fixed any of the encountered incompatibilities, set the variable back to ENFORCING at run time:

mysql> SET pxc_strict_mode=ENFORCING;

Also, switching back to ENFORCING may be done by restarting the node with the updated configuration file (on Debian and Ubuntu /etc/mysql/mysql.conf.d/mysqld.cnf; on CentOS and Red Hat /etc/my.cnf).

The configuration file layout has changed in Percona XtraDB Cluster 8.0¶

All configuration settings are stored in the default MySQL configuration file:

• Path on Debian and Ubuntu: /etc/mysql/mysql.conf.d/mysqld.cnf
• Path on Red Hat and CentOS: /etc/my.cnf

Before you start the upgrade, move your custom settings from /etc/mysql/percona-xtradb-cluster.conf.d/wsrep.cnf (on Debian and Ubuntu) or from /etc/percona-xtradb-cluster.conf.d/wsrep.cnf (on Red Hat and CentOS) to the new location accordingly.

caching_sha2_password is the default authentication plugin¶

In Percona XtraDB Cluster 8.0, the default authentication plugin is caching_sha2_password. The ProxySQL option –syncusers will not work if the Percona XtraDB Cluster user is created using caching_sha2_password. Use the mysql_native_password authentication plugin in these cases.

Be sure you are running on the latest 5.7 version before you upgrade to 8.0.

mysql_upgrade is part of SST¶

mysql_upgrade is now run automatically as part of SST. You do not have to run it manually when upgrading your system from an older version.

Scenario: No active parallel workload or with read-only workload¶

If there is no active parallel workload or the cluster has read-only workload while upgrading the nodes, complete the following procedure for each node in the cluster:

1. Shutdown one of the node 5.7 cluster nodes.
2. Remove 5.7 PXC packages without removing the data-directory.
3. Install Percona XtraDB Cluster 8.0 packages.
4. Restart the mysqld service.

This upgrade flow auto-detects the presence of the 5.7 data directory and trigger the upgrade as part of the node bootup process. The data directory is upgraded to be compatible with Percona XtraDB Cluster 8.0. Then the node joins the cluster and enters synced state. The 3-node cluster is restored with 2 nodes running Percona XtraDB Cluster 5.7 and 1 node running Percona XtraDB Cluster 8.0.

Percona XtraDB Cluster 8.0 uses Galera 4 while Percona XtraDB Cluster 5.7 uses Galera-3. The cluster will continue to use the protocol version 3 used in Galera 3 effectively limiting some of the functionality. With all nodes upgraded to version 8.0, protocol version 4 is applied.

mysql> USE mysql;
...
mysql> SELECT protocol_version from wsrep_cluster;
+------------------+
| protocol_version |
+------------------+
|                4 |
+------------------+
1 row in set (0.00 sec)

As soon as the last 5.7 node shuts down, the configuration of the remaining two nodes is updated to use protocol version 4. A new upgraded node will then join using protocol version 4 and the whole cluster will maintain protocol version 4 enabling the support for additional Galera 4 facilities.

It may take longer to join the last upgraded node since it will invite IST to obtain the configuration changes.

The situation was different for the previous and penultimate nodes since the donation of the configuration changes is not supported by protocol version 3 that they used.

With IST involved on joining the last node, the smart IST flow is triggered to take care of the upgrade even before MySQL starts to look at the data directory.

Scenario: Upgrading from Percona XtraDB Cluster 5.6 to Percona XtraDB Cluster 8.0¶

First, upgrade Percona XtraDB Cluster from 5.6 to the latest version of Percona XtraDB Cluster 5.7. Then proceed with the upgrade using the procedure described in Scenario: No active parallel workload or with read-only workload.