Codership Troubleshooting Articles

This is the Troubleshooting section of the Galera Knowledge Base (KB). It contains information on resolving problems you might experience with Galera Cluster. It includes articles on how to diagnose and address various performance and replication trouble. For articles related to performance and other ways to improve usage of Galera Cluster, see the :doc:` Best Practices <../best/index>` section of the KB.

Node Crashes during rsync SST

Length: 221 words; Published: ; Topic: State Transfers

When a new node joins a cluster, it will request data from the cluster. One node, known as a donor, will use a State Snapshot Transfer (SST) method to provide a full data copy to the new node, known as the joiner. This should work well, but it doesn’t always.

Requested State Transfer Failed

Length: 301 words; Published: ; Topic: State Transfers

When a new node joins a cluster, it will try to synchronize with the cluster by getting a full copy of the databases from one of the other nodes. Sometimes this will fail.

Cluster Stalls on ALTER

Length: 358 words; Published: ; Topic: SQL & Syntax Errors

There may be times in which a cluster will stall when an ALTER statement is executed on an unused table.

SQL Syntax Errors

Length: 159 words; Published: ; Topic: SQL & Syntax Errors

When a new node joins a cluster, it will request data from the cluster. One node, known as a donor, will use a State Snapshot Transfer (SST) method to provide a full data copy to the new node, known as the joiner. To get this snapshot, some administrators opt to use a Logical State Transfer Method, in particular mysqldump. This doesn’t always work well.

Multi-Master Conflicts

Length: 751 words; Published: ; Topic: Splits & Topology

These types of conflicts relate to multi-master database environments and typically involve inconsistencies of row amongst nodes.

Unknown Command Errors

Length: 599 words; Published: ; Topic: Splits & Topology

If a cluster experiences a temporary split—that is to say, a portion of the nodes loses connectivity to the Primary Component—when they reconnect, nodes from the former non-operational component drop their client connections. New connections to the database client will return Unknown command errors.

User Changes not Replicating

Length: 373 words; Published: ; Topic: Security

Galera replicates only InnoDB tables. Therefore, databases should not use other storage engines. However, the system tables contained in the mysql database use the MyISAM storage engine. This includes the user table and other tables containing user permissions. Since these tables are not replicated, you must make changes to them manually on each node.

Commit Failed for Reason 3

Length: 246 words; Published: ; Topic: Transactions

When you have wsrep_debug enabled, you may occasionally see a message noting that a commit has failed due to reason 3.