Converting the node role

The node roles of the host and SCVM include both master nodes and storage nodes.

When a node fails or needs to be relocated for workload balancing purposes, you can efficiently convert a master node to a storage node or vice versa through the AOC interface.

Procedure

1. In the host list on AOC, click the ellipsis (…) to the right of the target host or SCVM, and select Convert role.

2. In the pop-up Convert node role dialog, the system will perform a series of prechecks. If any check fails to meet the requirements, follow the recommended actions to manually adjust the configuration, and then click Retry to try converting the role again.

   • Converting master node to storage node

     Precheck item	Suggested operations when exit check fails
     All hosts in the cluster are in the healthy or not responding state.	Restore the host to a healthy state.
     The number of master nodes in this cluster will meet the requirement after conversion: After the role of a healthy master node is converted, the number of healthy master nodes in the cluster must be between 3 and 5 inclusive. After the role of a not responding master node is converted, the number of healthy master nodes in the cluster must be between 2 and 5 inclusive.	If any master node is in an unhealthy state, restore the node to a healthy state. If all master nodes are healthy but the number of healthy nodes does not meet the requirement, role conversion is not allowed.
     The ZooKeeper and MongoDB services in the cluster are running properly.	Fix the faults.
     The cluster has no data recovery in progress.	Wait for the data recovery to complete.
     There are no other hosts with the following statuses in the cluster: Being added; Entering maintenance mode; In maintenance mode; Being removed; Removal failed; Converting the role; Role conversion failed.	Wait for the host to complete ongoing tasks and exit the current state.
     The cluster is not upgrading.	Wait for the cluster upgrade to complete.
     (Active-active cluster only) The witness node in the active-active cluster is healthy.	Restore the witness node.

   • Converting storage node to master node

     Precheck item	Suggested operations when exit check fails
     All hosts in the cluster are in the healthy state, and the current host is not in maintenance mode.	If the current host is in maintenance mode, exit maintenance mode. If there are any hosts that are not in a healthy state, restore them to a healthy state.
     After the role of the current node is converted, the number of healthy master nodes in the cluster must be between 3 and 5.	If any master node is in an unhealthy state, restore the node to a healthy state. If all master nodes are healthy but the number of healthy nodes does not meet the requirement, role conversion is not allowed.
     The ZooKeeper and MongoDB services in the cluster are running properly.	Fix the faults.
     The cluster has no data recovery in progress.	Wait for the data recovery to complete.
     There are no other hosts with the following statuses in the cluster: Being added; Entering maintenance mode; In maintenance mode; Being removed; Removal failed; Converting the role; Role conversion failed.	Wait for the host to complete ongoing tasks and exit the current state.
     The cluster is not upgrading.	Wait for the cluster upgrade to complete.
     (Active-active cluster only) The witness node in the active-active cluster is healthy.	Restore the witness node.

3. If all check items meet the requirements, click Convert in the lower right corner of the dialog box.

   After submitting the role conversion task for the host, the page will display the task progress and whether the conversion is successful. If the conversion fails, select Retry to resubmit the task.