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Settings for the cluster including general settings, mail notifications, and thresholds.

CMON Settings

General Settings

Field Description
Cluster Name
  • Cluster name. This name will appear in the database cluster list and database cluster summary.
Staging Area
  • The staging area is a directory (created automatically) to store intermediate data, such as dump files, binaries, packages used in installations, upgrades or scaling. The staging area is automatically cleaned but should be big enough to hold dump files of your entire database.
  • Sudo command password (if SSH User* is not root) if running as sudoers. Change in CMON configuration file under sudo.
SSH User
  • Read-only. The user can SSH from the ClusterControl Server to the other nodes without a password. Change in CMON configuration file under os_user or osuser.
SSH Identity
  • Read-only. Change in CMON configuration file under ssh_identity.
  • The number of days you would like to keep historic data. Ensure you have enough disk space on the ClusterControl server if you want to store historic data.
Log Interval
  • How many minutes between automatic MySQL error log retrieval.

Starting from ClusterControl 1.9.7 (September 2023), ClusterControl GUI v2 is the default frontend graphical user interface (GUI) for ClusterControl. Note that the GUI v1 is considered a feature-freeze product with no future development. All new developments will be happening on ClusterControl GUI v2. See User Guide (GUI v2).

Email Notification Settings

Configures email notifications for alarms generated for your database cluster.

Field Description
Send email to
  • Recipient email address.
Send digests at
  • Send a digested (summary) email at this time every day for the selected recipient.
  • Timezone for the selected recipient.
The daily limit for non-digest email as
  • The maximum number of non-digest email notification should be sent per day for the selected recipient. -1 for unlimited.
  • Alarm/Event Category
Event Description
Network Network related messages, e.g host unreachable, SSH issues.
CmonDatabase Internal CMON database-related messages.
Mail Mail system-related messages.
Cluster Cluster related messages, e.g cluster failed.
ClusterConfiguration Cluster configuration messages, e.g software configuration messages.
ClusterRecovery Recovery messages like cluster or node recovery failures.
Node Message related to nodes, e.g node disconnected, missing GRANT, failed to start HAProxy, failed to start NDB cluster nodes.
Host Host related messages, e.g CPU/disk/RAM/swap alarms.
DbHealth Database health-related messages, e.g memory usage of MySQL servers, connections.
DB performance Alarms for long-running transactions and deadlocks
Software installation Software installation related messages.
Backup Messages about backups.
Unknown Other uncategorized messages.
  • Select how you want alarms/events to be delivered
Action Description
Ignore Ignore if an alarm raised.
Deliver Send notification immediately via email once an alarm raised.
Digest Send a summary of alarms raised every day at Send digests at

Runtime Configuration

Summarizes the active ClusterControl Controller (CMON) runtime configuration parameters and displays the versions of ClusterControl Controller and ClusterControl UI packages. All parameters listed here are loaded directly from cmon.cmon_configuration the table, displayed by the current cluster ID. You can filter out the variables by using the Search field on the top of the table. Each parameter has the Current Value (the active value loaded into ClusterControl) and also the Default Value (if undefined, ClusterControl will use this value) as well as a description of the parameter.

Some configuration parameters can be modified directly from the UI like swap_warning (Settings → Thresholds → Swap Warning) and backup_subdir (Backup → Settings → Default Backup Subdirectory). Some parameters have to be set inside the CMON configuration file for the respective cluster-ID.

Thus, there are two ways to modify the value of any parameter:

  1. Change the value directly from the UI if exists. This will save it into the cmon database. No cmon restart requires.
  2. Append the parameter line inside the CMON configuration file for the respective cluster /etc/cmon.d/cmon_X.cnf (where X is the cluster ID). This requires a cmon restart to get it loaded into the cmon database.

As a side note, the settings that are set through UI will always take precedence.


You can also run cmon --help-config to get the details of supported parameters.


Provides thresholds for warnings and critical events. Thresholds specify the threshold level at which an alarm will be triggered and notification will be sent via email to the list of recipients configured in the Email Notification Settings. Set your alarm thresholds for:

  • CPU, RAM, disk space, and swap utilization.
  • MySQL server memory utilization.
  • data memory, IndexMemory, tablespace, redo log and buffer utilization (MySQL Cluster).
Level Description
Warning Sets your warning threshold in percentage for a specific event.
Critical Sets your critical threshold in percentage for a specific event.


Manages graph settings and data capturing. On each database node, ClusterControl records up to 82 MySQL counters every db_stats_collection_interval defined in the CMON configuration file. The default is 30 seconds.

You can choose to view up to 20 counters in 2 or 3 columns layout on this page. The settings configured here affect the ClusterControl → Performance → Overview page.

Field Description
  • Filters the status variables available in the counter list.
Graph 1-N
  • Choose the enabled counter to be graphed.

Query Monitor

Manages how ClusterControl should perform query monitoring. It determines the output of:

  • ClusterControl → Overview → Cluster-Wide Queries
  • ClusterControl → Query Monitoring → Top Queries
  • ClusterControl → Query Monitoring → Query Outliers

Changes that happened on this page do not require the CMON service to restart.

  • MySQL Local Query Override
    • Choose whether you want ClusterControl to override the local MySQL query sampling:
      • Yes – The local MySQL configuration settings inside my.cnf for long_query_time and log_queries_not_using_indexes will be used.
      • No – ClusterControl uses Long Query Time and Log queries not using indexes will be used across all MySQL Servers.
  • Long Query Time
    • Collects queries taking longer than Long Query Time seconds:
      • 0 – All queries.
      • 0.1 – Only queries taking more than 0.1 seconds will be accounted for.
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