Help Center/ Elastic Load Balance/ User Guide/ User Guide for Shared Load Balancers/ Backend Server/ Cloud Servers
Updated on 2024-09-20 GMT+08:00
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Cloud Servers

When you use ELB to route requests, ensure that at least one backend server is running properly and can receive requests routed by the load balancer.

After a backend server is unbound from a load balancer, the backend server does not receive requests forwarded by the load balancer, but the backend server is disassociated from the load balancer. You can add the backend server to the backend server group again when traffic increases or the reliability needs to be enhanced.

Notes and Constraints

  • Only servers in the same VPC as the load balancer can be added.
  • ECSs and BMSs can be added as backend servers. If Transfer Client IP Address is enabled for the listeners of a shared load balancer, only BMSs with certain flavors can be added as backend servers.

Adding a Cloud Server

  1. Go to the backend server group list page.
  2. On the Backend Server Groups page, click the name of the backend server group.
  3. Switch to the Backend Servers tab and click Add on the right.
  4. Search for backend servers using specified keywords.
  5. Specify the weights and ports for the backend servers, and click Finish.

    Backend server ports can be set in batches.

Modifying Cloud Server Ports/Weights

  1. Go to the backend server group list page.
  2. On the Backend Server Groups page, click the name of the target backend server group.
  3. On the Backend Servers tab, click Backend Servers.
  4. Select the cloud servers and click Modify Weight up above the cloud server list.
  5. In the displayed dialog box, modify ports/weights as you need.
    • Changing the weight of a single cloud server: Set the weight in the Weight column.
    • Modifying the weights of multiple cloud servers: Select the target cloud servers and set the weight next to Batch Modify Weights and click OK.

    You can set the weights of multiple cloud servers to 0 to block them from receiving requests routed by each load balancer.

  6. Click OK.

Removing a Cloud Server

If a cloud server is removed, requests are still routed to it. This is because a persistent connection is established between the load balancer and the backend server and requests are routed to this server until the TCP connection times out. If no data is transmitted over this TCP connection after it times out, ELB disconnects the connection.

  1. Go to the backend server group list page.
  2. On the Backend Server Groups page, click the name of the target backend server group.
  3. Switch to the Backend Servers tab and click Backend Servers.
  4. Select the cloud servers you want to remove and click Remove above the cloud server list.
  5. In the displayed dialog box, click OK.
Parent Topic: Backend Server