Managing the Cluster

The complete cluster configuration and status check process can be performed with the command cluster. In addition to the process, we will use the command application to initiate instances and define a master instance.

mt4adm@vmdf-giskard:~$ sudo orbit cluster --help
Usage: orbit cluster <command>

High Availability and Disaster Recovery settings tools

Arguments:
<command>    Control the application services status:
             [start|stop|restart|config|status]

Flags:
      --help               Show context-sensitive help.

      --ip=STRING          The local node IP
  -n, --nodes=NODES,...    Cluster nodes list
  -s, --segment=0          Define which network segment this node is in
  -l, --latency="low"      Latency between nodes: [low|medium|high]
      --force              Force the command execution, never prompt
      --show

Creating the cluster

To create the cluster you need at least two instances. As an example, we will call the instances "A" and "B". Follow the following order to assemble the cluster.

• Activate instance A both in activation license and application activation;

• Start the application in instance A with the command orbit application start;

• The –ip argument must be used with the IP of the instance that the command is running

• Configure the cluster in instance A by entering the parameter –ip with the IP of instance A and the parameter –nodes with the IP's of instance A and B respectively;

• Determine instance A as master using the command orbit application master

• Start the cluster in instance A with the command orbit cluster start and wait at least 1 minute for normalization;

• Activate instance B with the activation license and keep the application inactive;

• Configure the cluster in instance B by entering the parameter –ip with the IP of instance B and the parameter –nodes with the IP's of instance A and B respectively;

• Start the cluster in instance B with the command orbit cluster start and wait at least 1 minute for normalization;

Instance A

mt4adm@vmdf-giskard:~$ sudo orbit application master
The application services will be stopped or restarted during the process.
Are you sure you want to proceed: y

Application: Active
Replication: Inactive
Instance:    Primary

mt4adm@vmdf-giskard:~$ sudo orbit cluster config  
    --ip=172.18.77.184  
    --nodes=172.18.77.184,172.18.77.186  
    --segment=0  
    --latency="low"

Are you sure you want to proceed: y
Done!
No errors reported

mt4adm@vmdf-giskard:~$ sudo orbit cluster start --ip=172.18.77.184
Are you sure you want to proceed: y
Done!
No errors reported

Instance B

mt4adm@vmdf-giskard:~$ sudo orbit cluster config  
    --ip=172.18.77.186  
    --nodes=172.18.77.184,172.18.77.186  
    --segment=1  
    --latency="low"

Are you sure you want to proceed: y
Done!
No errors reported

mt4adm@vmdf-giskard:~$ sudo orbit cluster start --ip=172.18.77.186
Are you sure you want to proceed: y
Done!
No errors reported

caution

For the proper functioning of the cluster, the network latency between nodes must be at most 30ms.

Cluster status

Using the orbit cluster status command you can observe several properties of the cluster. As there is a lot of information, we will not list all the details in the manual. But we will present the essential information to understand if the cluster is active and problem-free.

Pay attention to the final block of the status, called "Cluster nodes". In this block you will see who are the cluster members and the timestamp of synchronization between them. There is also the status of the current instance that should be marked as "synced".

mt4adm@vmdf-giskard:~$ sudo orbit cluster status

...

============================================================

Cluster nodes

Cluster member: ID [0] - UUID [64661644-b0df-11ea-80b2-8ee23c1303c0] -
    Hostname [vmdf-giskard-3232290344] - Timestamp [1592428528]
Cluster member: ID [1] - UUID [9dff00d8-b0df-11ea-86c4-83725d654e03] -
    Hostname [vmdf-giskard-3232290348] - Timestamp [1592428528]

Cluster UUID: 64679b9f-b0df-11ea-a6e5-67ba900fecc0

vmdf-giskard details: status=synced
vmdf-giskard is primary node ?: 1

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