Netscaler realizes the Control of active and standby service

Many people often ask how to implement the master / slave function of two or more servers with the same business, that is, the same VIP is used externally, and the backend corresponds to two or more real servers, but normally only one or more servers are used as master servers, and only the remaining servers take over the business as standby servers when there is a problem with the master server.

From a technical point of view, this requirement is unwise, but as long as it exists, it is reasonable, and you can't completely influence what the customer thinks. Since there is a demand, as a powerful Netscaler, there is a solution, but this requirement is contrary to the load balancer design, so we do not quite understand how to configure. Then write a blog so that you don't often answer similar questions.

There are three ways to achieve the above requirements on Netscaler (it seems that some convinced built-in related algorithms are really convinced). Please choose the specific method according to the specific business situation.

1. Realize it through backup vserver

Logic diagram

Configuration:

Create two new vserver and add their own service to the two vserver

Service corresponding to two vserver (here two web servers are replaced with different ports of one web)

Set up a backup vs on the vs of primary

Access to primary normally

Access to backup normally

Disable port 80 to simulate primary server failure

At this point, primary becomes down, but the status of the actual effect is still UP

Users still have no problem accessing 192.168.0.57 (primary's IP), while hostname remains the same.

2. Realize it through listen policy

Logic diagram

Configuration

Create two new vs with ports of both 80

Primary binds 80-port service,primary2 to 81-port service to simulate two servers

Screenshot outline

Configure listen policy for primary2

Access the vs of primary under normal circumstances

Disable the 80-port service to simulate the failure of the main server, and the vs changes to the following state

Visit the business again and hit the vs of primary2

Business is normal

3. Realize it through monitor

Logic diagram

Configuration

Check reverse

The status of service under normal circumstances. Backup is down.

Create a new vserver and bind two service

Disable port 80 simulation failure, service statu

Access business is normal.

Through a deep understanding of the parameters of Netscaler, we can provide a variety of ideas to solve the problem.