Unable to Perform Elastic Resize for Amazon Redshift Cluster? We can help you.

Recently, one of our customers tried to perform an elastic resize via AWS CloudFormation for his Amazon Redshift cluster.

However, it performed a classic resize instead.

Here, at Bobcares, we assist our customers with several AWS queries as part of our AWS Support Services.

Today, let us see what leads to this and how we can troubleshoot it.

Unable to Perform Elastic Resize for Amazon Redshift Cluster

If we resize the cluster using the Amazon Redshift console, it does not register in the AWS CloudFormation template.

Instead, if we use the AWS CloudFormation template we can ensure that the numberofNodes parameter updates.

Otherwise, Amazon Redshift might perform a classic resize, despite meeting the resize requirements.

This behavior is a result when there are no changes to the node count since its last resize.

Generally, a classic resize by Amazon Redshift happen if we don’t meet any of these requirements:

• Only the numberofNodes parameter modifies.
• For dc2.large or ds2.xlarge node types, we can only double the node count or decrease the node count by half of the original cluster.
• Similarly, for dc2.8xlarge or ds2.8xlarge node types, we can resize up to two times the original node count, or resize down to half of the original node count.
• The number of nodes cannot exceed the number of slices.

How to Troubleshoot?

To confirm the actual number of nodes in the cluster, we can check the Amazon Redshift console.

Then we can verify if it matches the numberofNodes parameter in the AWS CloudFormation template.

To retrieve information from AWS CloudTrail and to determine root cause analysis, we can use the DescribeClusters API.

We look at the elasticResizeNumberOfNodeOptions parameter to verify whether the Amazon Redshift cluster is eligible for an elastic resize.

Suppose, the parameter does not list an option to update node count.

This confirms that the cluster slices fail to meet the elastic resize requirements.

[Stuck with the Elastic Resize? We’d be happy to help you out]

Conclusion

In short, we saw how our Support Techs troubleshoot the Elastic Resize issue with the Amazon Redshift Cluster.