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Managing Performance and Scaling for Amazon Aurora MySQL

Scaling Aurora MySQL DB Instances

You can scale Aurora MySQL DB instances in two ways, instance scaling and read scaling. For more information about read scaling, see Read Scaling.

You can scale your Aurora MySQL DB cluster by modifying the DB instance class for each DB instance in the DB cluster. Aurora MySQL supports several DB instance classes optimized for Aurora. The following table describes the specifications of the DB instance classes supported by Aurora MySQL.

Instance Class	vCPU	ECU	Memory (GiB)
db.t2.small	1	1	2
db.t2.medium	2	2	4
db.r3.large	2	6.5	15.25
db.r3.xlarge	4	13	30.5
db.r3.2xlarge	8	26	61
db.r3.4xlarge	16	52	122
db.r3.8xlarge	32	104	244
db.r4.large	2	7	15.25
db.r4.xlarge	4	13.5	30.5
db.r4.2xlarge	8	27	61
db.r4.4xlarge	16	53	122
db.r4.8xlarge	32	99	244
db.r4.16xlarge	64	195	488

Maximum Connections to an Aurora MySQL DB Instance

The maximum number of connections allowed to an Aurora MySQL DB instance is determined by the max_connections parameter in the instance-level parameter group for the DB instance.

The following table lists the resulting default value of max_connections for each DB instance class available to Aurora MySQL. You can increase the maximum number of connections to your Aurora MySQL DB instance by scaling the instance up to a DB instance class with more memory, or by setting a larger value for the max_connections parameter, up to 16,000.

Instance Class	max_connections Default Value
db.t2.small	45
db.t2.medium	90
db.r3.large	1000
db.r3.xlarge	2000
db.r3.2xlarge	3000
db.r3.4xlarge	4000
db.r3.8xlarge	5000
db.r4.large	1000
db.r4.xlarge	2000
db.r4.2xlarge	3000
db.r4.4xlarge	4000
db.r4.8xlarge	5000
db.r4.16xlarge	6000

If you create a new parameter group to customize your own default for the connection limit, you'll see that the default connection limit is derived using a formula based on the DBInstanceClassMemory value. As shown in the preceding table, the formula produces connection limits that increase by 1000 as the memory doubles between progressively larger R3 and R4 instances, and by 45 for different memory sizes of T2 instances. The much lower connectivity limits for T2 instances are because T2 instances are intended only for development and test scenarios, not for production workloads.