Change the configurations of an instance

• Instances that use local disks
• Standard instances that use cloud disks

• The cluster architecture imposes requirements on Lua scripts. After you change an instance to the cluster architecture, the Lua scripts may be lost because script content does not meet the requirements. You must back up the Lua scripts in advance. For more information, see Limits on commands supported by cluster instances.
• If you change the configurations of an instance, the instance may experience one or two transient connections that last for less than 30 seconds. For Lettuce clients, the instance may be disconnected for 2 to 10 minutes.
  Note We recommend that you set the Switching Time parameter to Switch Within Maintenance Window when you change the configurations of an instance. In this case, the instance configurations are changed and transient connections occur in the next maintenance window.
• To synchronize incremental data from the original instance to the new instance and prevent dual write caused by the Domain Name System (DNS) cache, the instance becomes read-only for less than 1 minute during the configuration change. This ensures data consistency between the new and original instances.
• To ensure higher performance and stability, the system updates the minor version of an instance to the latest version during the configuration change.

• Cluster instances that use cloud disks

During the configuration change, ApsaraDB for Redis migrates slots to the newly added data shards. This can help achieve imperceptible scaling. During this process, the latency remains under 100 milliseconds.

• Before you change a non-cluster instance into a cluster instance, you must evaluate how the command limits of cluster instances affect your workloads. For more information, see Limits on commands supported by cluster instances.
• If you change the architecture of an instance (such as from standard to cluster), the existing alert settings become invalid and the data flashback feature is disabled.
  • To continue using alerts, you must reconfigure alert settings. For more information, see Alert settings.
  • To continue using data flashback, you must re-enable the feature. For more information, see Use data flashback to restore data by point in time.
• If a private endpoint is allocated to an ApsaraDB for Redis cluster instance and you want to change the number of shards for the instance, you can only double the current number of shards. For more information about private endpoints, see Enable the direct connection mode. For example, if the original instance has two shards, you can scale the instance only to four shards. You cannot directly scale the instance to eight shards. If you want to scale the instance from two shards to eight shards, use one of the following methods:
  • Scale the instance from two shards to four shards. Then, scale the instance from four shards to eight shards.
  • Release the private endpoint. Then, directly scale the instance to eight shards. For more information, see Release a private endpoint for an ApsaraDB for Redis instance.

• You can change the quantity but not the specifications of data shards.
• An instance can contain 2 to 256 shards. You can add or reduce up to 64 shards each time.
• The specifications of the shards that you want to add are the same as those of existing shards and cannot be modified.

For more information, see Adjust the number of shards for an ApsaraDB for Redis instance.

• You cannot change the architecture of a child instance (such as from cluster to standard).
• To change the configurations of a child instance in a distributed instance, you must change the configurations of all the other child instances in the distributed instance in the same way. Otherwise, performance or capacity issues may occur.
• You can only double the current number of shards for a child instance. For example, if the original instance has two shards, you can scale the instance only to four shards. You cannot directly scale the instance to eight shards.
  Note If you want to scale the instance from two shards to eight shards, you can scale the instance from two shards to four shards and then scale the instance from four shards to eight shards.