Managing Doradus via JMX

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[Doradus Configuration and Operation](https://github.com/dell-oss/Doradus/wiki/Doradus Configuration and Operation): Managing Doradus via JMX

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Doradus extends the Java JMX API with monitoring and administration features. JMX functions can be accessed with off-the-shelf JMX applications such as JConsole, which is bundled with the Java SDK. JMX functions are available from two MXBean objects:

• com.dell.doradus.ServerMonitor: This MXBean provides information about the Doradus server including its configuration, start time, and statistics about REST commands.

• com.dell.doradus.StorageManager: This MXBean provides information used by the Doradus Task Manager to conduct background tasks. It also provides operations for modifying tasks and to execute Cassandra backup and recovery tasks.

JMX functions only collect and return information when the Doradus MBean service (com.dell.doradus.mbeans.MBeanService) has been initialized. This is always the case when the server is started as a standalone process but optional when Doradus is embedded within another application.

ServerMonitor

ServerMonitor provides the following attributes:

Attribute Name	Description
AllRequests	Provides a composite set of values about REST API requests such as the total number of requests, the number of failed requests, and the reason of the last request failure.
ConnectionsCount	The current number of REST API connections.
DatabaseLink	Indicates if the Cassandra database being accessed is local (1), remote (2), or not yet known (0).
RecentRequests	A composite value set similar to AllRequests but for REST API requests made since the last time RecentRequests was accessed.
ReleaseVersion	The Doradus Server release version.
ServerConfig	Lists configuration doradus.yaml settings, including value overridden by runtime arguments.
StartTime	Provides the start time of the Doradus server as a Date.getTime() value.
Throughput	Provides a histogram of REST API request response times in seconds for various sampling rates (e.g., 1 minute, 5 minutes, 15 minutes.)
WorkingDirectory	The working directory of the Doradus server.

StorageManager

StorageManager is operative only when the Task Manager service has been initialized (com.dell.doradus.service.taskmanager.TaskManagerService). This is always the case when the server is started as a standalone process but optional when Doradus is embedded within another application. StorageManager provides the following attributes:

Attribute Name	Description
AppNames	The Doradus application names known to the Task Manager.
GlobalDefaultSettings	The global task schedule settings, which are used for tasks that do not have a more specific (e.g., application- or table-specific) schedule default. The global schedule is usually "never", meaning no default schedule is applied to tasks.
JobList	The list of tasks currently executing.
NodesCount	The number of Cassandra nodes in the cluster.
OS	The operating system of the Doradus server.
OperationMode	The operation mode of the first connected Cassandra mode (NORMAL, LEAVING, JOINING, etc.)
RecentJob	Attributes about the most recent job executed through the StorageManager interface.
ReleaseVersion	The Doradus server release version.
StartMode	The execution mode of the first connected Cassandra node: 1 (FOREGROUND), 2 (BACKGROUND), or 0 (UNKNOWN).

The StorageManager MXBean also provides operations that perform basic administrative functions, summarized below:

Operation Name	Description
getJobByID	Get the status of a job with a specific ID.
startCreateSnapshot	Start a task to create a backup snapshot of the first Cassandra node connected to the Doradus server, assigning the snapshot a name.
startDeleteSnapshot	Delete a backup snapshot with a given name.
startRestoreFromSnapshot	Restore the Cassandra node connected to the Doradus server from a given snapshot game.
sendInterruptTaskCommand	Interrupt an executing task with a given name, belonging to a given application.
sendSuspectSchedulingCommand	Suspend the scheduling of a task with a given name, belonging to a given application.
sendResumeSchedulingCommand	Resume the scheduling of a task with a given name, belonging to a given application.
getAppSettings	Get the default task schedule settings for a given application name.
getTaskStatus	Get the status of a task with a given name, belonging to a given application.