Help Center/ Elastic Load Balance/ Drawer/ Buying a Load Balancer/ Elastic and Fixed Specifications
Updated on 2025-07-25 GMT+08:00

Elastic and Fixed Specifications

Differences

When you create a dedicated load balancer, you can select elastic or fixed specifications based on your service requirements. Table 1 lists the differences between the two specifications.

Table 1 Specifications comparison

Item

Elastic

Fixed

Application scenarios

  • For fluctuating traffic
  • When you urgently need to use resources but only temporarily
  • For stable traffic
  • When you need to use resources for a long time

Billing mode

Pay-per-use

  • Pay-per-use
  • Yearly/Monthly

Billing Item

  • LCU
  • Load balancer

LCU

Capabilities

Same

Available specifications are displayed on the console and may vary depending on the resources in different regions.

ELB Specifications and Performance

Load balancers are available in different specifications as described in Table 2. Choose the specifications that best meet your needs. When traffic exceeds what defined in your selected specifications, new requests will be discarded.

The load balancer performance increases with the number of AZs. Elastic Specifications and Fixed Specifications show the maximum performance of a load balancer in a single AZ.

Table 2 Dimensions of each specification

Dimension

Description

Connections per second (CPS)

The number of new connections that a load balancer can establish per second.

If the number reaches the CPS that is defined in the elastic specifications, new requests will be discarded to ensure the performance of established connections.

Maximum Connections

The maximum number of concurrent connections that a load balancer can handle.

If the number reaches the maximum connections that is defined in the elastic specifications, new requests will be discarded to ensure the performance of established connections.

Queries per second (QPS)

The number of HTTP or HTTPS requests sent to a backend server per second.

If the QPS reaches that is defined in the elastic specifications, new requests will be discarded to ensure the performance of established connections.

Bandwidth (Mbit/s)

The maximum amount of data that can be transmitted over a load balancer per second.