There could be scenarios where you might need to stop and start a node in order to perform some maintenance activities on it. Stopping a node requires that you first stop the database instances, then the storage service, and finally the node. The reverse order applies when starting a node. This section provides you with the steps on how to stop and start nodes.
Shut Down Nodes
To stop a cluster / node, follow these steps:
Shut down the database(s)
Shut Down Storage
- Check EXAoperation Running On Management Node
- Shut Down Data Nodes
- Shut Down Management Node
Before you shut down the database(s), check for running operations. In EXAoperation, go to Services > EXASolution and check for running operations. There should be no running operation when you shut down a node or cluster.
If you stop the database while there are operations running, these operations will be aborted. It is recommended to wait until all running operations have completed before stopping the database.
- Select the database instances that should be shutdown and click Shutdown.
- Refresh the page until the status of all instances change from Running to Created.
- Check for running operations before you shut down the storages/volumes. In EXAoperation, go to Services > EXAStorage. The Recovery field should be n/a for all volumes. Click Shutdown Storage Service.
- The services will be shut down, and the EXAStorage screen looks as follows:
If you stop the storage while operations are running, these operations will be aborted. It is recommended to wait until all running operations have completed before stopping the database.
Check to ensure that EXAoperation is running on the Management node. The management node is the only node that boots from the local drive. For this reason, EXAoperation must be running on the management node, and not on a data node, because if you shut down data nodes with EXAoperation running on it, you will not have access to EXAoperation anymore.
In EXAoperation, go to Services > EXAoperation and make sure that the node displayed is the management server (usually 'n0010'):
If any node other than the license server is shown here, it means EXAoperation is not running on the management node. In this case, you need to select the management node from the drop down list and click Move to specified Node before you shut down the data nodes.
- Check the status of the cluster node before you shut it down. In EXAoperation, go to Configuration > Nodes. The State/Op. field should be Running and Active for all nodes.
- Select all data nodes and then select Shutdown from the Actions ... drop down list, and click Execute.
- The nodes will be shut down. They appear with a state Unknown once they are shut down.
For additional information on actions you can perform on the nodes, refer to the Actions on Nodes section.
In the License Nodes group box, click Shutdown to shut down the management node.
Start Up Nodes
To start a cluster/node, perform the following steps:
Start Management Node
- Login to EXAoperation
- Start the data nodes
- Start Storage Service
- Start Database(s)
To start the management node, you can
- Physical hardware: power on the management node using the power button.
- Virtual Environment: use your virtualization software to power on the management node.
Enter the management node's IP address in a browser, and login using the user name and password for your administrator user.
Depending on your environment, the steps to start up the data nodes can be different:
|Physical hardware, no IPMI configured: start node manually.||Physically power on the nodes in the cluster.|
|Physical hardware, IPMI configured: start nodes using EXAoperation.||
|Virtual environment||Use your virtualization software to power on the node.|
You can follow the node's boot up process in a log service. Click on Monitoring and click the log service you set up that excludes LOAD events. To see the latest events, click the Tail tab.
Before continuing, ensure that all nodes have a state of Running. If any of the nodes has a state of Offline, the data on these nodes will be deleted and the system will attempt to recover the data from other nodes when the storage is started.
- In EXAoperation, go to Services > EXAStorage. When the storage service is not running, the screen looks as follows:
- Click Startup Storage Service.The storage service starts up and the screen looks like this after a few minutes:
To start the database(s), in EXAoperation, go to Services > EXASolution. Select the database and click Start.
Once the database is up, there is a green light beside the database name in the EXASolution screen. This indicates the database is accepting client connections.
Automate Cluster Stop / Start Process
In addition to stopping and starting Exasol cluster services from EXAoperation, you can also automate this process by using a Python script. For more information on how to automate the stop and start process of Exasol cluster services, refer to the GitHub repository.