`gcs.fc_limit`

CRITICALWARNING

2 automated checks 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_limit. Do not assume it is dynamic or SET 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: MariaDB KB Percona Docs

What is checked

Rules that reference this variable, with their severity and what each rule detects:

CRITICAL Increase gcs.fc_limit via wsrep_provider_options (e.g., SET GLOBAL wsrep_provider_options='gcs.fc_limit=200') and investigate why the applier on this node is slow (storage I/O, applier threads, large transactions).
WARNING Investigate the applier backlog on this node before flow control triggers: check storage I/O, increase applier threads, or raise gcs.fc_limit if the hardware can keep up.

Tuning guidance

Recommended actions:
- Increase gcs.fc_limit via wsrep_provider_options (e.g., SET GLOBAL wsrep_provider_options='gcs.fc_limit=200') and investigate why the applier on this node is slow (storage I/O, applier threads, large transactions).
- Investigate the applier backlog on this node before flow control triggers: check storage I/O, increase applier threads, or raise gcs.fc_limit if the hardware can keep up.
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.

Generated from the MySQL Advisor documentation build. Dynamic Yes/No reflects the excerpt aligned with Oracle MySQL 8.4 reference material consumed by this project.