User guide

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While Amazon Redshift is performing maintenance, it terminates any queries or other operations that are
in progress. If there are no maintenance tasks to perform during the scheduled maintenance window,
your cluster continues to operate normally until the next scheduled maintenance window.
You can change the scheduled maintenance window by modifying the cluster, either programmatically
or by using the Amazon Redshift console. The window must be at least 30 minutes and not longer than
24 hours. For more information, see Managing Clusters Using the Console (p. 13).
Default Disk Space Alarm
When you create an Amazon Redshift cluster, you can optionally configure an Amazon CloudWatch alarm
to monitor the average percentage of disk space that is used across all of the nodes in your cluster.We’ll
refer to this alarm as the default disk space alarm.
The purpose of default disk space alarm is to help you monitor the storage capacity of your cluster.You
can configure this alarm based on the needs of your data warehouse. For example, you can use the
warning as an indicator that you might need to resize your cluster, either to a different node type or to
add nodes, or perhaps to purchase reserved nodes for future expansion.
The default disk space alarm triggers when disk usage reaches or exceeds a specified percentage for a
certain number of times and at a specified duration. By default, this alarm triggers when the percentage
that you specify is reached, and stays at or above that percentage for five minutes or longer.You can
edit the default values after you launch the cluster.
When the CloudWatch alarm triggers, Amazon Simple Notification Service (Amazon SNS) sends a
notification to specified recipients to warn them that the percentage threshold is reached. Amazon SNS
uses a topic to specify the recipients and message that are sent in a notification.You can use an existing
Amazon SNS topic; otherwise, a topic is created based on the settings that you specify when you launch
the cluster.You can edit the topic for this alarm after you launch the cluster. For more information about
creating Amazon SNS topics, see Getting Started with Amazon Simple Notification Service.
After you launch the cluster, you can view and edit the alarm from the cluster’s Status window under
CloudWatch Alarms. The name is percentage-disk-space-used-default-<string>.You can open
the alarm to view the Amazon SNS topic that it is associated with and edit alarm settings. If you did not
select an existing Amazon SNS topic to use, the one created for you is named
<clustername>-default-alarms (<recipient>); for example, examplecluster-default-alarms
([e-mail]).
For more information about configuring and editing the default disk space alarm, see Creating a
Cluster (p. 14) and Editing the Default Disk Space Alarm (p. 28).
Note
If you delete your cluster, the alarm associated with the cluster will not be deleted but it will not
trigger.You can delete the alarm from the CloudWatch console if you no longer need it.
Renaming Clusters
You can rename a cluster if you want the cluster to use a different name. Because the endpoint to your
cluster includes the cluster name (also referred to as the cluster identifier), the endpoint will change to
use the new name after the rename finishes. For example, if you have a cluster named examplecluster
and rename it to newcluster, the endpoint will change to use the newcluster identifier. Any applications
that connect to the cluster must be updated with the new endpoint.
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Amazon Redshift Management Guide
Default Disk Space Alarm