gcs.fc_master_slave
INFO
1 automated check cover this variable.
Overview
- Purpose
- Configuration or diagnostic item referenced in tuning reviews. It may be vendor-specific, renamed between versions, or not present in the bundled MySQL 8.4 summary table under this exact name.
- Dynamic (MySQL 8.4 reference)
- Not found in the bundled MySQL 8.4 variable summary extract under
gcs.fc_master_slave. Do not assume it is dynamic orSET GLOBAL-able — open the manual for your exact product and version. - Default value
- See vendor documentation.
- Version and product notes
- Compare MySQL, MariaDB, and Percona Server manuals; names changed across releases (for example replication terminology).
- Documentation
- https://dev.mysql.com/doc/refman/8.4/en/server-system-variable-reference.html
- Other vendors
What is checked
Rules that reference this variable, with their severity and what each rule detects:
- INFO If your application performs writes exclusively on one node, enabling gcs.fc_master_slave=yes (or gcs.fc_single_primary=yes on newer Galera) disables flow control on the writer node and improves write throughput.
Tuning guidance
- Recommended actions:
- If your application performs writes exclusively on one node, enabling gcs.fc_master_slave=yes (or gcs.fc_single_primary=yes on newer Galera) disables flow control on the writer node and improves write throughput.
- Trade-offs: Galera cluster settings affect write throughput, consistency, and failover behavior. Flow control protects slow nodes but can stall the entire cluster. SST method choice affects donor impact during node joins.
Example
Look up this name (and synonyms) in vendor documentation before changing anything in production.