ApsaraDB for Redis is integrated with the bandwidth auto scaling feature of Database Autonomy Service (DAS). After you enable this feature for an ApsaraDB for Redis instance, DAS scales up the instance bandwidth if the bandwidth usage of the instance reaches the specified threshold. This helps you handle unexpected or scheduled traffic spikes and focus on business improvement.
Prerequisites
The instance is an instance of the ApsaraDB for Redis Community Edition or a performance-enhanced or hybrid-storage instance of the ApsaraDB for Redis Enhanced Edition (Tair). For more information about performance-enhanced instances and hybrid-storage instances, see Performance-enhanced instances and Hybrid-storage instances (phased out).
Scenarios
The bandwidth of an instance varies based on the instance type. If the bandwidth in use reaches the allocated bandwidth, network congestion may occur and instance performance may deteriorate. To prevent these situations, you can enable the bandwidth auto scaling feature. A bandwidth adjustment helps you increase bandwidth at a lower cost than an instance specification change and can help prevent transient connections.
Scenario | Description |
---|---|
Handle traffic spikes | You can adjust the bandwidth of the instance to handle traffic spikes during promotional events such as a flash sale. After these events end, you can decrease the bandwidth of the instance to reduce costs. |
Mitigate impacts on your business | If a large number of read and write operations are performed on large keys within a short period of time, you must temporarily increase the bandwidth of the instance to mitigate impacts on your business and to reserve time to process these operations. |
Deal with skewed requests at low costs | If your instance is in the cluster or read/write splitting architecture, some data
shards or read replicas of the instance are more frequently accessed than others.
For more information about the cluster and read/write splitting architecture, see
Cluster master-replica instances and Read/write splitting instances. As a result, the bandwidth consumption of these data shards or read replicas frequently
reaches the allocated bandwidths. However, the usage of the bandwidths that are allocated
to other data shards or read replicas is low.
After you enable the bandwidth auto scaling feature, the system identifies the data shards or read replicas whose allocated bandwidth is insufficient and increases the bandwidth for them. You do not need to manually increase the bandwidth or change the specifications of the instance to which these data shards or read replicas belong. This reduces costs and facilitates O&M. |
Process
After you enable the bandwidth auto scaling feature, the system performs the following operations based on the auto scaling policy and observation window that you configure. The increment or decrement is calculated by the system.
- If the bandwidth increase threshold of an instance is reached, the system increases the bandwidth and continues to monitor bandwidth usage. If the threshold is reached again, the system increases the bandwidth again. The bandwidth can be increased up to three times the default bandwidth of the instance type. If you want to increase this bandwidth limit, you can upgrade the specifications of your instance and then adjust the bandwidth.
- If the bandwidth decrease threshold of an instance is reached, the system decreases the bandwidth and continues to monitor bandwidth usage. If the threshold is reached again, the system decreases the bandwidth again. The bandwidth can be decreased to the default bandwidth of the instance type.
- If your instance is in the cluster or read/write splitting architecture, the system monitors the bandwidth usage of data shards and read replicas and increases the bandwidth only for the data shards or read replicas whose allocated bandwidth is insufficient.
- If you enable the subscription service, you are notified of every increase or decrease by the notification method that you select, such as an email. For more information about how to enable the subscription service, see the relevant section in this topic.
- To ensure that DAS can access resources of your ApsaraDB for Redis instance, the system authorizes DAS to use the AliyunServiceRoleForDAS role after you enable this feature.
Limits
- The bandwidth of an instance can be increased to up to three times the bandwidth that is provided for the instance type. If you require higher bandwidth for an instance, you can change the specifications of the instance or upgrade the instance from a standard instance to a cluster instance. For more information about the standard architecture, see Standard master-replica instances. Then, you can increase the bandwidth of the instance. If the increased bandwidth is still insufficient, submit a ticket.
- If you perform the following operations on an instance, the extra bandwidth that you
purchased automatically becomes invalid and you will receive a refund. You must re-adjust
the bandwidth of the instance based on your business requirements. By default, the
expiration time of the previously purchased extra bandwidth is inherited.
- Upgrade the major version of the instance. For more information, see Upgrade the major version.
- Change the specifications of the instance. For more information, see Change the configurations of an instance. If the instance is a standard master-replica instance, the bandwidth settings remain valid after you change the specifications of the instance.
Note If the instance is a cluster master-replica instance, the distribution of keys changes after you change the specifications of the instance. As a result, the data shards to which hot keys belong change. In this case, the bandwidth settings become invalid.
- Change the zone of the instance. For more information, see Migrate an instance across zones. If the instance is a standard master-replica instance, the bandwidth settings remain valid.
Billing
You are charged per day based on the amount and usage duration of the extra bandwidth that you purchase. The fees vary based on the region that you select. For more information, see Billable items and prices.
Procedure
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