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노드란?
클러스터를 구성하는 호스트 서버의 단위 입니다.
두개의 노드로 클러스터를 구성하게 되면 투 노드 클러스터, 하나의 노드로만 구성하게 되면 싱글노드 클러스터로 구성됩니다.
MCCS에서는 클러스터에 최대 2개의 노드를 등록할 수 있습니다.
노드속성
노드의 속성은 노드의 속성 뷰에서 파악할 수 있습니다.
MCCS 콘솔의 노드 관리 뷰에서 노드 선택 후 오른쪽의 'ㄴ 속성값' 탭의 상세 정보를 볼수 있습니다.
회색으로 표기된 값은 읽기 전용입니다. 이 값들은 그룹 상태를 나타내기 위한 정보입니다. 흰색으로 표기된 값은 사용자에 의해 정의된, 수정가능한 값입니다. 아래에 일부가 설명되어 있습니다.
[그림] 그룹 속성 화면
노드 속성값
속성 | 타입 | 설명 | 기본값 | 수정 |
| BootMode | Boolean | MCCS 서비스 기동 시 운영체제 시작 후 그룹 자동 시작 여부를 나타냅니다. | X | |
| HostID | String | 노드에 입력된 라이선스의 MAC을 나타냅니다. | X | |
| LicenseType | String | 노드에 입력된 라이선스 타입을 나타냅니다. | X | |
ExpirationDate | String | 노드에 라이선스 만료 날짜를 나타냅니다. |
| X |
IsolationTestAddress | String | Isolation을 테스트할 IP를 입력합니다. |
| O |
NodeName | String | 노드 이름을 나타냅니다. |
| X |
NodeState | String | 노드 상태를 나타냅니다. |
| X |
PrimaryHB | String | MCCS 설정된 Primary 핫빗 주소를 나타냅니다. |
| X |
| PrimaryHBStatus | String | 설정된 Primary 핫빗 상태를 나타냅니다. | X | |
SecondaryHB | String | MCCS 설정된 Secondary 핫빗 주소를 나타냅니다. |
| X |
| SecondaryHBStatus | String | 설정된 Secondary 핫빗 상태를 나타냅니다. | X | |
| StandAlone | Boolean | StandAlone 작동 여부를 나타냅니다. | X |
CLI 사용(mcnode 명령)
노드에 관한 명령을 전달 합니다. 노드에 대해 속성 조회, 속성 값 변경, 라이선스 입력, 서포트 파일 다운로드 명령을 내릴 수 있습니다.
노드 속성의 상세한 내용은 "챕터 9. 속성 - 노드 속성값" 편을 참조해 주십시오.
Syntax
...
Node Attribute
Node attribute can be identified from NodeAttributes view of MCCS console.
From the node management view of MCCS console, select node, then select the ‘Node Attributes’ tab located on right top of detailed information panel.
The values of gray colored are for read only. They just contain and show the information of node state. The values of white colored are configurable by user definition. Below is description of some of them.
[Figure] Node Attribute View
Attribute | Description | Type | Default | Edit | Note |
| BootMode | It is value that indicate whether or not to been started according to the bootMode value setting when MCCS service starts. | BOOLEAN | X | ||
| ExpirationDate | It shows license MAC of the node. | STRING | |||
| HostID | It shows license MAC of the node. | STRING | X | ||
| IsolationTestAddresses | It enters the IP address to test Isolation. It is recommended the reliable IP address. | IP ADDRESS | O | ||
| LicenseType | It shows license type of the node. | STRING | X | ||
NodeName | It indicated the name of the node. You can use an actual host name or nickname. | NAME |
| X | |
NodeState | It indicated the state of the node. | STRING |
| X | |
PrimaryHB | It shows an IP address of the Primary Heartbeat defined in the MCCS server. | IP ADDRESS |
| X | |
| PrimaryHBStatus | It indicates state of primary heartbeat. | IP ADDRESS | X | ||
SecondaryHB | It shows an IP address of the Secondary Heartbeat defined in the MCCS server. | IP ADDRESS |
| X | |
| SecondaryHBStatus | It indicates state of secondary heartbeat. | IP ADDRESS | X | ||
| StandAlone | It indicates whether standalone mode or not. | BOOLEAN | false | X |
How MCCS Works
MCCS connects nodes as one cluster through heartbeat connection.
Action of the cluster is decided by the state and role of the node, and node states are decided not only by the system state but also the state of heartbeat connection.
Following are node states for Cluster Mode.
Node states of the Cluster Mode
| State | Description |
|---|---|
| EXITED | This is a state where MCCS engine is terminated. |
| INITING | This is a state before configuring the heartbeat after starting the engine. This is initial state before both nodes communicate each other through heartbeat network and collect mutual status of node state after MCCS engine is started. This state is normally changed to the LOCAL_BUILD or REMOTE_BUILD state, but if there is a problem with the configuration or physical environment, it remains in the INITING state, or is automatically terminated to the EXITED state. |
| LOCAL_BUILD | When every node in the cluster is in the INITING state, the node with the highest priority at establishing of heartbeat communication is changed to the LOCAL_BUILD state, and the node in this state forms a cluster database from the local configuration file(%MCCS_HOME%\config\main.json). Only one node within the cluster goes through this state to the RUNNING state, and other nodes undergo the REMOTE_BUILD state that receives information from that node. |
| REMOTE_BUILD | When a node in the INITING state detects a node in the RUNNING state through heartbeat communication, it establishes by downloading the configuration. |
| RUNNING | This is the state when establishing a configuration database through the LOCAL_BUILD or REMOTE_BUILD is completed, and starts agents and group administrators of all the resources defined at this state. |
| FAULTED | When all the heartbeats with the node in the RUNNING state are disconnected, the node is FAULTED. |
Action step according to Node State
Following is the process of the change of the node state of MCCS.
[Figure] MCCS Action step according to Node State
Redundancy of heartbeat communication path
Heartbeat has the vital role of synchronizing the state and determining the failure state between nodes.
Therefore, when the system is being operated, it must be redundant to guarantee a state of being available for communication at all times.
Also, to determine the isolation of the network, one of the heartbeat networks must be established as a network available for communication with the service network or nodes other than the cluster node.
Node Fault
When all the heartbeat communication is disconnected for a certain amount of time, the node is declared to be in failure state.
The final decision on the discontinuance of heartbeat communication is made by the ICMP test.
When both nodes cannot communicate with each other within a defined amount of time, MCCS define the state as split, isolation and remote node fault.
Discontinuance of heartbeat
If all of the heartbeat communication is disconnected, both nodes cannot exchange the mutual state. Service recovery and process are determined by whether the opposite node is declared as a failure, or simply in a state in which the communication paths between nodes are disconnected.
Split Brain
If the interval of heartbeat network disconnections is greater than the limit set in the cluster attribute, you can suspect instability of the entire heartbeat network instead of node failures.
Thus, it is deemed that the heartbeat node status cannot be trusted and it does not detect system failures but maintains the current status.
When heartbeat communication is restored, the nodes in the clusters will restart the MCCS service and return to the running status.
If not, it will wait until heartbeat communication is restored in INITING state.
Isolation
Before declaring the opposite node as a failure even when all the heartbeats are disconnected within a certain time period, MCCS check the local node is disconnected from the whole network.
If the node can communicate to authorized network points such as gateway or DNS server, the local node is not disconnected, and it can be concluded that the opposite node is in a failure state and will not try to recover.
It that is not the case, it can be considered as isolation state.
Since standby node considers local node has a failure while local is trying to recover the service, service on local node needs to be terminated as soon as possible.
Remote Node Fault
When a local node cannot communicate to opposite node within a defined timeout and it is not in an isolation state, local node will try to keep its state as RUNNING, and bring ONLINE the services which taken OFFLINE from remote node.
How to Change the Node Name
- In the web console, select the node management view and select the node to change the name for.
- After selecting a node, click right mouse button and click on the 'Node Name Change' menu.
[Figure] Node Name Change Selected - The screen will prompt you to enter the new node name to change.
Enter the node name to change.
[Figure] New Node Name Input - In the node management view of web console, you can check the newly changed node name.
CLI Use(mcnode command)
It sends the node commands. You can command to inquire about or change the node attributes, enter the license or download the support file.
| Info |
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When you install MCCS, the initial user account ID is set to 'admin' and the password is set to 'password'. |
Syntax
| Code Block |
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mcnode [-u userid -pw password] [-ip node_ip_address] -command [-a attribute] [-l license] [-p download_path] |
Options
...
-h
...
도움말을 출력합니다.
...
-n
...
Options
| Option | Description |
-h | Display Help. |
| -u | Designate the user account ID. |
| -pw | Enter user password. |
-n | It defines the node to access to execute command. If omitted, it will access to execute command for local node. |
-a | If the [modify] 명령일 경우 변경할 속성과 속성값을 지정합니다command is used, set the attribute and the attribute values to change. |
-p | 서포트 파일 다운 받을 경로를 지정합니다. path 지정 생략시 user.home으로 다운로드 됩니다Designate the path for downloading the support file. If you do not enter the path, it will be downloaded to 'user.home'. |
| -l | 지정한 노드의 입력할 라이선스 값을 지정합니다Enter the license value to be entered for the designated node. |
Example
...
modify
Modify the attribute values for testNode-1의 노드 속성값을 수정합니다. 1.
| Code Block |
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mcnode -u admin -pw password -modify -n testNodeTestNode-1 -a IsolationTestAddressattribute attribute_value |
license
Enter the license for testNode-1
...
.
...
| Code Block |
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mcnode -u admin -pw password -license -n TestNode-1 [ -all ] license_value |
support
Download the support file of testNode-1
...
to c:\
...
.
(If you enter -
...
all, it will create the support file for all the nodes and then download them.)
| Code Block |
|---|
mcnode -u admin -pw password -supprot [-n TestNode-1 ([ -all) ] -p c:\ |
list
노드의 속성 리스트를 보여줍니다.
(noname 입력시 입력한 해당 노드에 대한 속성 값만 출력.)
...
Show the list of node attributes.
(If you enter node name, it will only display the attribute values for the node entered.)
| Code Block |
|---|
mcnode -u admin -pw password -list ([-n nodename)] |