Amazon DynamoDB | Auto Scaling Flashcards
How does Amazon DynamoDB achieve high uptime and durability?
Auto Scaling
Amazon DynamoDB | Database
To achieve high uptime and durability, Amazon DynamoDB synchronously replicates data across three facilities within an AWS Region.
What is DynamoDB Auto Scaling?
Auto Scaling
Amazon DynamoDB | Database
DynamoDB Auto Scaling is a fully managed feature that automatically scales up or down provisioned read and write capacity of a DynamoDB table or a global secondary index, as application requests increase or decrease.
Why do I need to use Auto Scaling?
Auto Scaling
Amazon DynamoDB | Database
Auto Scaling eliminates the guesswork involved in provisioning adequate capacity when creating new tables and reduces the operational burden of continuously monitoring consumed throughput and adjusting provisioned capacity manually. Auto Scaling helps ensure application availability and reduces costs from unused provisioned capacity.
What application request patterns and workload are suited for Auto Scaling?
Auto Scaling
Amazon DynamoDB | Database
Auto Scaling is ideally suited for request patterns that are uniform, predictable, with sustained high and low throughput usage that lasts for several minutes to hours.
How can I enable Auto Scaling for a DynamoDB table or global secondary index?
Auto Scaling
Amazon DynamoDB | Database
From the DynamoDB console, when you create a new table, leave the ‘Use default settings’ option checked, to enable Auto Scaling and apply the same settings for global secondary indexes for the table. If you uncheck ‘Use default settings’, you can either set provisioned capacity manually or enable Auto Scaling with custom values for target utilization and minimum and maximum capacity. For existing tables, you can enable Auto Scaling or change existing Auto Scaling settings by navigating to the ‘Capacity’ tab and for indexes, you can enable Auto Scaling from under the ‘Indexes’ tab. Auto Scaling can also be programmatically managed using CLI or AWS SDK. Please refer to the DynamoDB developer guide to learn more.
What are settings I can configure for Auto Scaling?
Auto Scaling
Amazon DynamoDB | Database
There are three configurable settings for Auto Scaling: Target Utilization, the percentage of actual consumed throughput to total provisioned throughput, at a point in time, the Minimum capacity to which Auto Scaling can scale down to, and Maximum capacity, to which the Auto Scaling can scale up to. The default value for Target Utilization is 70% (allowed range is 20% - 80% in one percent increments), minimum capacity is 1 unit and maximum capacity is the table limit for your account in the region. Please refer to the Limits in DynamoDB page for region-level default table limits.
Can I change the settings of an existing Auto Scaling policy?
Auto Scaling
Amazon DynamoDB | Database
Yes, you can change the settings of an existing Auto Scaling policy at any time, by navigating to the ‘Capacity’ tab in the management console or programmatically from the CLI or SDK using the AutoScaling APIs.
How does Auto Scaling work?
Auto Scaling
Amazon DynamoDB | Database
When you create a new Auto Scaling policy for your DynamoDB table, Amazon CloudWatch alarms are created with thresholds for target utilization you specify, calculated based on consumed and provisioned capacity metrics published to CloudWatch. If the table’s actual utilization deviates from target for a specific length of time, the CloudWatch alarms activates Auto Scaling, which evaluates your policy and in turn makes an UpdateTable API request to DynamoDB to dynamically increase (or decrease) the table’s provisioned throughput capacity to bring the actual utilization closer to the target.
Can I enable a single Auto Scaling policy across multiple tables in multiple regions?
Auto Scaling
Amazon DynamoDB | Database
No, an Auto Scaling policy can only be set to a single table or a global secondary indexes within a single region.
Can I force an Auto Scaling policy to scale up to maximum capacity or scale down to minimum capacity instantly?
Auto Scaling
Amazon DynamoDB | Database
No, scaling up instantly to maximum capacity or scaling down to minimum capacity is not supported. Instead, you can temporarily disable Auto Scaling, set desired capacity you need manually for required duration, and re-enable Auto Scaling later.
Where can I monitor the scaling actions triggered by Auto Scaling?
Auto Scaling
Amazon DynamoDB | Database
You can monitor status of scaling actions triggered by Auto Scaling under the ‘Capacity’ tab in the management console and from CloudWatch graphs under the ‘Metrics’ tab.
How can I tell if a table has an active Auto Scaling policy or not?
Auto Scaling
Amazon DynamoDB | Database
From the DynamoDB console, click on Tables in the left menu, to bring up the list view of all DynamoDB tables in your account. For tables with an active Auto Scaling policy, the ‘Auto Scaling’ column shows either READ_CAPACITY, WRITE_CAPACITY or READ_AND_WRITE depending on whether Auto Scaling is enabled for read or write or both. Additionally, under the ‘Table details’ section of the ‘Overview’ tab of a table, the provisioned capacity label shows whether Auto Scaling is enabled for read, write or both.
What happens to the Auto Scaling policy when I delete a table or global secondary index with an active policy?
Auto Scaling
Amazon DynamoDB | Database
When you delete a table or global secondary index from the console, its Auto Scaling policy and supporting Cloud Watch alarms are also deleted.
Are there any additional costs to use Auto Scaling?
Auto Scaling
Amazon DynamoDB | Database
No, there are no additional cost to using Auto Scaling, beyond what you already pay for DynamoDB and CloudWatch alarms. To learn about DynamoDB pricing, please visit the DynamoDB pricing page.
