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이 페이지의 주요 내용

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What is an Agent?

Agent is a program designed to manage the resources.

Each resource type has a corresponding agent. Agents control resources according to its state. The agent aware the resource state and communicates them to MCCS.

A resource cannot be brought online or taken offline without an agent, and the actions required to do either differ from resource to resource. 

For an example, filesystem will be mounted, unlocked, and have the write access to make a disk resource online. However, to make a process resource online is to execute the program.

MCCS agents are multithreaded which means a single agent manages multiple resources in the its type in a cluster.

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An agent is the internal MCCS program used to manage the resource.
MCCS uses an agent to command or monitor the resource. Depending on the resource type, an agent performs a proper function for each resource.
For instance, making a shared disk go online is to mount and unlock a disk, and allow write access.
But making a process go online is to run the program in the designated path.

 

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Agent State Change

Agent State

Agent state can be checked from agent state value from resource state view of detailed information panel.

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Agent State

State Description

Detached

It is in disabled state where agent thread hasn't started yet, therefore resource is not monitored yet.
In this case, Enabled value is false in the resource attribute.

Opening

It is preparing to monitor where resource is enabled. 
Enabled value has been changed to true in the resource attribute.

Probing

It is probing and verifying stage where the resource is ready to be used.

Online

Resource is in Online state and is being monitored.

Offline

Resource is in Offline state and is being monitored.
When resource is taken offline for failure, agent considers its state as Offline.

GoingOffline

Agent is taking offline a resource which it is online state.

GoingOfflineWait

It is a state command which agent takes online a resource was completed and resource is ready to offline state.

GoingOnline

Agent is bringing online a resource which it is offline state.

GoingOnlineWait

It is a state command which agent brings online a resource is completed and resource is ready to online.

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When a resource has been enabled, an agent will start monitor a resource after probing and its state will be changed. 
After determining the state based on the results of the monitoring, agent gets the command and  and its state will be changed. 
Below is the flow of the change of agent state. 

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