ec2 vCPU 内存
m4.large 2 8
m4.xlarge 4 16
m4.2xlarge 8 32
m4.4xlarge 16 64
m4.10xlarge 40 160
m4.16xlarge 64 256

RDS： vCPU 内存
db.m4.16xlarge 64 256
db.m4.10xlarge 40 160
db.m4.4xlarge 16 64
db.m4.2xlarge 8 32
db.m4.xlarge 4 16
db.m4.large 2 8