You can set the parameters of automatic specification changes on the Basic Information page of your ApsaraDB PolarDB MySQL-compatible edition cluster, ApsaraDB PolarDB MySQL-compatible edition Cluster Edition instances automatically scale out or scale in based on the parameters that you configure. This topic describes how to configure automatic specification change parameters on the Basic Information page of a ApsaraDB PolarDB MySQL-compatible edition cluster.
- Only ApsaraDB PolarDB MySQL-compatible edition Cluster Edition is supported. Single Node and Archive Database are not supported. For more information about the three editions of PolarDB for MySQL, see Product editions.
- No tasks for specification changes for your PolarDB cluster are in the pending state.
- Your ApsaraDB PolarDB MySQL-compatible edition clusters are pay-as-you-go clusters. Subscription clusters do not support the automatic specification change feature.
For information about the pricing rules, see Configuration change fees.
- You can upgrade or downgrade the specifications of a cluster as a whole. You cannot upgrade or downgrade the specifications of individual nodes in the cluster.
- Upgrading or downgrading the specifications of a cluster does not have any impact on the existing data in the cluster.
- You may experience PolarDB service interruptions for a few seconds when you change specifications. During this time, you cannot perform some operations. We recommend that you change specifications during off-peak hours and make sure that your applications can automatically reconnect to the cluster.
- In most scenarios, it takes more time to execute read-only requests than read and write requests. The time required to execute read-only requests may further increase when you change the specifications of a PolarDB cluster.
- Log on to the PolarDB console.
- In the upper-left corner of the console, select the region where the cluster is deployed.
- On the Clusters page, find the cluster for which you want to configure automatic specification change parameters and click the cluster ID.
- On the Overview page, click Settings in the upper-right corner of the Database Nodes section.
- In the dialog box that appears, specify the following parameters.
Parameter Description Auto Scaling-out Specifies whether to enable the automatic scale-out feature. Observation Period If the CPU utilization is greater than or equal to the specified value during the observation period, PolarDB automatically adds nodes or upgrades the specifications of your cluster after the observation period expires. This ensures that the cluster can handle the read and write requests that the cluster received. For example, if the observation period is 5 minutes and the time required for automatic scale-out in 10 minutes, you must wait 15 minutes to check the scale-out effect. CPU Usage The threshold based on which automatic scale-out is triggered. If the average CPU utilization is greater than or equal to the specified value, automatic scale-out is triggered. Maximum Specification The upper limit of the specifications based on which you can upgrade your clusters. After automatic scale-out is triggered, the system gradually upgrades the specifications of your PolarDB cluster to the upper limit. For example, the specifications can be upgraded from 4 cores to 8 cores and then to 16 cores. Maximum Number of Read-only Nodes The maximum number of read-only nodes that can be automatically added to the cluster. After automatic scale-out is triggered, the read-only nodes of the PolarDB cluster are added one by one until the upper limit is reached.Note The nodes that are automatically added are associated with the default endpoint of your cluster. If you use a custom endpoint, you must specify whether these nodes are automatically associated with the endpoint by using the Automatically Associate New Nodes parameter. For more information about Automatically Associate New Nodes, see Manage a cluster endpoint. Auto Scaling-in Specifies whether to enable the automatic scale-in feature.Note After you turn on Automatic Scale-down/in, if the CPU utilization remains at less than 30% for more than 99% of the quiescent period, automatic scale-in is triggered after the quiescent period expires. The specifications of the PolarDB cluster are gradually scaled in to the original specifications. Quiescent Period The minimum interval between two automatic scale-in operations or two automatic scale-out operations. During a quiescent period, PolarDB continuously tracks whether the trigger conditions for automatic scale-out or scale-in are fulfilled. However, automatic scale-out or scale-in is not triggered. If a quiescent period and an observation period expire at the same time and the CPU utilization reaches the threshold within the observation period, PolarDB automatically triggers automatic scale-out when the two periods expire.
- Click OK.