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18.2 Replication Dashboard Tabs

This section describes the tabs of the Replication Dashboard.

Important

The Max Replication Delay field displays the total amount of replication delay which exists on the monitored topologies.

To display a replication group, choose a group from the Replication Group drop-down list.

Important

Clicking the refresh icon, adjacent to the Replication Group drop-down list, forces a re-discovery of all replication groups.

Topology

The Topology tab graphically displays the replication topology of the selected group.

Figure 18.2 Replication Topology Graph

Replication topology tab

This tab contains the following:

  • Topology graph: graphically displays the replication setup, enabling you to reposition the nodes for better visibility. To highlight an individual node and all related channels, hover the mouse cursor over the node.

  • Show Channel Names: enables or disables the display of channel names on the channel lines.

  • Legend : displays the meaning of each of the following graphical elements.

    • Node OK

    • Replication Issues

    • Node/Replication Down

    • Node Unmonitored

    • Async Fetch OK

    • Async Fetch Down

    • Semi-Sync Fetch OK

    • Semi-Sync Fetch Down

    • Link Status Unknown

Note

The topology graph displays semi-synchronous links only if both source and replica use the semi-sync plugins.

Group Status

The Group Status tab displays information on the status of the members of the replication group. Each instance expands to display detailed information in a drill-down.

Note

Data displayed in red indicates a problem with your configuration, while green indicates preferred settings.

Table 18.1 Group Status Columns

Name Description

Instance

Name of the monitored instance.

Fetch State

Displays the current status of the fetch operations. If the replica successfully retrieved data from the source, the icon is green. If the replication has not stopped because of an error, the icon is yellow. If the state is unknown, either because the instance is currently unmonitored, or no replication is taking place, the icon is red and the errors are displayed in a tooltip.

Apply State

Displays the current status of the apply operations. If the changes are successfully applied to the replica, the icon is green. If the apply operation was stopped, but no error occurred, the icon is yellow. If the apply operation stops because of an error, the icon is red and the error displayed in a tooltip.

Time Behind

Amount of time the replica is behind the source. N/A is displayed for sources. If there is a problem with the Fetch or Apply state, Unknown is displayed.

Read Only

Displays whether the node is read-only. N/A is displayed for sources.

GTID Enabled

Displays if the server is using GTIDs.

Binary Log Format

Displays the format used by the binary log.

Node Type

Displays the type of node. Source or Replica. If the replication type is multi-source, the node can be Replica/Source.

Channels

Displays the number of channels used by this instance.

Version

Displays the version of the MySQL instance.


The instance drill downs contain different information depending on if the instance is a source or a replica, and also depends on the type of replication in use. Each replica also contains a tab listing all the instances from which it is receiving updates.

  • Source drill down contents:

    • Node Status: graphs the source load in running connections, queries per second, and the average response time. The server IDs are also provided.

    • Local Binary Log Status: displays the details of the local binary log, such as name, position, and GTID set.

    • Binary Log Statistics: graphs the average read/writes per second, log file latency and total space usage.

      Note

      This frame requires sys schema to display all graphs. If sys schema is not installed on the node, only the Total Space Usage graph is displayed.

    • Most Appropriate Candidates for Source Promotion (best candidate on top): lists the replicas which are eligible for promotion to source.

      For a replica to be eligible for promotion to source, it must have the same gtid mode as the source. If gtid mode and binary logging are disabled, the replica cannot be promoted. Such replicas are listed in red with a message explaining why they are not eligible for promotion.

      Ordering of candidates is based on a scoring system. To be listed near the top of the list, the replica must have at least 70% of all transactions performed as transactions retrieved from a source, and no more than 30% of total transactions are transactions performed directly on the replica and not originating with a source. Then higher retrieved percentage and lower errant percentage improve the ranking of the replica. Higher ranking means higher chance of promotion.

    • Semi-Synchronous Replication: this frame is present for both asynchronous and semi-synchronous types, but is only populated if semi-synchronous replication is in use. If semi-synchronous replication is running, this section contains graphs showing the Sessions Waiting, Waits, and transaction status.

  • Replica drill-down contents:

    • Node Status: graphs the replica load in running connections, queries per second, and the average response time. The server IDs are also provided.

    • Source Replication Status: displays a tab for every source replicating to the selected replica. Each tab displays the following:

      • Fetch Status: displays graphs and information on the status of the data retrieval from the source.

      • Filter / Delay Status: displays the defined and remaining delays and any filtered databases or specific tables.

      • Apply Status: displays the current apply status, the last executed GTID set, and so on. The status by worker is also displayed.

        Note

        The Info column of the Status by Worker section requires the user have the Query Analysis Example and Explain Data permission set to at least Read-Only. If this permission is not granted, the Info column cannot be populated.

      • Source Configuration: displays the instance name, port, and username of the source.

      • Channel Configuration: displays the channel configuration information.

      • Secure Connection Configuration: displays all SSL-related information for the monitored instance.

      • Replication Configuration: displays all information related to the configuration of the replication process.

It is also possible to edit and delete connections from this tab. Clicking the drop-down list next to the instance opens the instance context menu. For more information on this menu, see Group and Instance Context Menu.

Group Statistics

The Group Statistics tab graphs the activity of all members of the group. You can change the data displayed using the Graph Time Range selections. If a range is selected for which there is no data, no graph is displayed.

The following graphs are available:

  • Database Activity - All MySQL Instances: displays the total number of SELECT, INSERT, UPDATE, REPLACE, DELETE, and CALL statements performed on all members of the selected group.

  • Connections Running - Per MySQL Instance: displays the running connections for each member of the group.

  • Database Queries - Per MySQL Instance: displays the number of queries performed against each member of the group.

Figure 18.3 Replication Group Statistics

Replication dashboard group statistics tab

Error History

The Error History tab displays all errors logged for the members of the selected group. The time of the error, type of error and error message are displayed.


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