Health checks
You can check the health of a cluster or node from the ACM. For clusters, there are two basic checks: the health of the nodes in the cluster and the health of the cluster itself. The health checks for a node are whether the node is online and, as you would expect, the health of the node itself.
Cluster health checks
Cluster health checks appear near the top of a Cluster view. For example, here is the panel view of a cluster with the two health checks:
Figure 1 - A cluster panel with its two health checks
The health check at the top of the panel indicates that 2 of the 2 nodes in the cluster are online:
Clicking on this green bar takes you to the detailed view of the cluster. From there you can see the individual nodes and their status.
The second health check indicates that 6 of the 6 cluster health checks passed:
Clicking on this green bar shows you the health check dialog:
Figure 2 - The Health Checks dialog
The cluster health checks are based on six SELECT statements executed against the cluster and its infrastructure. The six statements look at the following cluster properties:
- Access point availability
- Distributed query availability
- Zookeeper availability
- Zookeeper contents
- Readonly replicas
- Delayed inserts
Clicking any of the checks shows the SQL statement used in the check along with its results:
Figure 3 - Details of a particular cluster health check
Depending on the cluster’s status, you may see other indicators:
| Health check | Meaning |
|---|---|
|
The cluster or node is rescaling |
|
The cluster or node is being terminated |
|
The cluster or node is stopped |
Node health checks
The basic “Node is online” check appears next to the node name in the Nodes view of the cluster:
Figure 4 - The Nodes view of a cluster
Opening the Node view shows more details:
Figure 5 - The health checks for a single node in the cluster
The first health check indicates that the node is online:
The second health check indicates that 5 of the 5 node health checks passed:
Clicking on this green bar takes you to a more detailed view of the health checks and their results, similar to Figure 11 above.