gcs.fc_single_primary
This page is part of MariaDB's Documentation.
The parent of this page is: wsrep Provider Options for MariaDB Enterprise Server
Topics on this page:
Overview
In 11.4 ES, 10.6 ES, 10.6 CS, 10.5 ES, 10.5 CS, 10.4 ES, 10.4 CS:
Defines whether there is more than one source of replication
In 10.3 ES, 10.3 CS, 10.2 ES, 10.2 CS:
Not present
The wsrep_provider_options system variable applies to MariaDB Enterprise Cluster, powered by Galera and to Galera Cluster available with MariaDB Community Server. This page relates specifically to the gcs.fc_wsrep_provider_options.
See also: wsrep Provider Options for MariaDB Enterprise Server 11.4, in 10.6 ES, in 10.5 ES, in 10.4 ES, in 10.3 ES, in 10.2 ES, in 10.6 CS, in 10.5 CS, in 10.4 CS, in 10.3 CS, and in 10.2 CS
DETAILS
As the number of nodes in the cluster grows, the larger the calculated gcs.fc_limit gets. The number of writes from the nodes also increases.
When the gcs.fc_single_primary option value is set to NO (multi-primary), the gcs.fc_limit parameter is dynamically modified to give more margin for each node to be a bit further behind applying writes.
The gcs.fc_limit option is modified by the square root of the cluster size. For example, in a four-node cluster the gcs.fc_limit is two times higher than the base value. This is done to compensate for the increasing replication rate noise.
Attribute | Value |
|---|---|
Option Name | gcs.fc_single_primary |
Default Value | NO |
Dynamic | NO |
Debug |
|
EXAMPLES
Display Current Value
wsrep_provider_options define optional settings the node passes to the wsrep provider.
To display current wsrep_provider_options values:
SHOW GLOBAL VARIABLES LIKE 'wsrep_provider_options';
The expected output will display the option and the value. Options with no default value, for example SSL options, will not be displayed in the output.
Set in Configuration File
When changing a setting for a wsrep_
Options are set in the my.cnf configuration file. Use the ; delimiter to set multiple options.
The configuration file must be updated on each node. A restart to each node is needed for changes to take effect.
Use a quoted string that includes every option where you want to override the default value. Options that are not in the list will reset to their default value.
To set the option in the configuration file:
wsrep_provider_options='gcs.fc_single_primary=YES;gcache.debug=YES;gcs.fc_limit=NO;socket.send_buf_size=NO;evs.keepalive_period=PT3S'
Set Dynamically
The gcs.fc_single_primary option cannot be set dynamically. It can only be set in the configuration file.
Trying to change a non-dynamic option with SET results in an error:
ERROR 1210 (HY000): Incorrect arguments to SET
CHANGE HISTORY
Release Series | History |
|---|---|
11.4 Enterprise |
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10.6 Enterprise |
|
10.6 Community |
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10.5 Enterprise |
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10.5 Community |
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10.4 Enterprise |
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10.4 Community |
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10.3 Enterprise |
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10.3 Community |
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10.2 Enterprise |
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10.2 Community |
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