5.3. Checking Dataservice Status

The cctrl command provides the main interface to the dataservice information and control. The current status and configuration of the dataservice can be determined by using the ls command within the cctrl shell:

shell> cctrl
Continuent Tungsten 4.0.7 build 111
connect to 'alpha@host1'
alpha: session established
[LOGICAL:EXPERT] /alpha > ls

COORDINATOR[host1:AUTOMATIC:ONLINE]

ROUTERS:
+----------------------------------------------------------------------------+
|connector@host1[8805](ONLINE, created=0, active=0)                          |
|connector@host2[12039](ONLINE, created=0, active=0)                         |
|connector@host3[12712](ONLINE, created=0, active=0)                         |
+----------------------------------------------------------------------------+

DATASOURCES:
+----------------------------------------------------------------------------+
|host1(master:ONLINE, progress=3, THL latency=0.561)                         |
|STATUS [OK] [2013/05/03 09:11:10 PM BST]                                    |
+----------------------------------------------------------------------------+
|  MANAGER(state=ONLINE)                                                     |
|  REPLICATOR(role=master, state=ONLINE)                                     |
|  DATASERVER(state=ONLINE)                                                  |
|  CONNECTIONS(created=0, active=0)                                          |
+----------------------------------------------------------------------------+

+----------------------------------------------------------------------------+
|host2(slave:ONLINE, progress=3, latency=1.243)                              |
|STATUS [OK] [2013/05/04 05:40:43 AM BST]                                    |
+----------------------------------------------------------------------------+
|  MANAGER(state=ONLINE)                                                     |
|  REPLICATOR(role=slave, master=host1, state=ONLINE)                        |
|  DATASERVER(state=ONLINE)                                                  |
|  CONNECTIONS(created=0, active=0)                                          |
+----------------------------------------------------------------------------+

+----------------------------------------------------------------------------+
|host3(slave:ONLINE, progress=3, latency=0.000)                              |
|STATUS [OK] [2013/05/04 07:40:12 AM BST]                                    |
+----------------------------------------------------------------------------+
|  MANAGER(state=ONLINE)                                                     |
|  REPLICATOR(role=slave, master=host1, state=ONLINE)                        |
|  DATASERVER(state=ONLINE)                                                  |
|  CONNECTIONS(created=0, active=0)                                          |
+----------------------------------------------------------------------------+

The output consists of the following major sections:

  • COORDINATOR

    The coordinator is the node in the dataservice that is acting as the manager for the dataservice. The coordinator is decided upon within the dataservice by a consensus agreement, and the coordinator can change in the event of a failure of the existing coordinator. The coordinator is always the oldest datasource within the group that manages the dataservice, and does not need to be the same host as the master.

    The information about the coordinator is described in the following square brackets as HOSTNAME:POLICY:STATUS , where:

    • HOSTNAME

      The hostname of the current coordinator.

    • POLICY

      The current policy manager mode, which describes how the manager will respond to certain events. For example, in AUTOMATIC mode the manager will respond to issues and problems automatically, for example by performing an automatic master switch during a failover event.

      For more information on policy modes, see Section 5.4, “Policy Modes” .

    • STATUS

      The current status of the coordinator host.

  • ROUTERS

    A list of the currently configured SQL routers (using Tungsten Connector™)that are directing queries to the datasources. In the example, the dataservice consists of three routers, each connected to all of the configured data sources. The information output includes a summary of the number of connections made through the router, and the number of active connections to each router.

  • DATASOURCES

    The DATASOURCES section lists detailed information providing one block for each configured datasource. The header block of the datasource output describes the overall status of the datasource:

    +----------------------------------------------------------------------------+
    |host1(master:ONLINE, progress=3, THL latency=0.561)                         |
    |STATUS [OK] [2013/05/03 09:11:10 PM BST]                                    |
    +----------------------------------------------------------------------------+

    The first line describes the host and status information:

    • Hostname of the datasource (host1))

    • Current role within the dataservice and status of the datasource. For more information on roles, see Section 5.3.3, “Understanding Datasource Roles” . For information on datasource states, see Section 5.3.4, “Understanding Datasource States” .

    • The progress indicates the current sequence number from the THL for the datasource.

    • The THL latency shows the current latency of the datasource. For a master datasource using MySQL, this is the latency between the data being written to the MySQL binary log and being processed in the THL. For a slave, it shows the latency between the original commit (from the master) and the application on the slave.

    The second line provides a more detailed current status, and the time since the status was last changed. In the event of a change of status, for example to the SHUNNED or OFFLINE state, the time will indicate how long the node has been in that status.

  • The remaining lines of the datasource description provide detailed information about each of the remaining services on the datasource and their status. The list will depend on the assigned roles and parameters for each datasource. It is important to note that each service has a status that is independent of the overall datasource status.

    • |  MANAGER(state=ONLINE)                                                     |

      The Manager service, and the current status of the manager. If a configured datasource is down, has recently been restarted, or the manager has been stopped, the status may be offline.

    • |  REPLICATOR(role=slave, master=host1, state=ONLINE)                     |

      The Tungsten Replicator service, which replicates data between hosts. The status shows the current role (slave), the master host, and the current status of the replicator.

    • |  DATASERVER(state=ONLINE)                                                  |

      The status of the dataserver service, which indicates the status of the underlying database service.

    • |  CONNECTIONS(created=0, active=0)                                          |

      The Tungsten Connector service, showing the number of connections have been created on this service, and the number that are currently active.

The main service status output, as provided by ls at the top level, provides a quick overview of the overall status of the dataservice. More detailed information on each service, and the current status of the individual services can be monitored and managed through cctrl .