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This article focuses on "Oracle ADG deployment Architecture, change and Emergency response Analysis". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Next, let the editor take you to learn "Oracle ADG deployment architecture, change and emergency response analysis"!

1. What is Oracle ADG?

To put it simply, ADG is a disaster recovery architecture of Oracle, which ensures that when an exception occurs at the primary site (often using the RAC architecture), the emergency response switches to the standby ADG site to continue to provide services.

The distance between master and slave sites can be in the same data center, in the same data center, in the same city, or in different places, and it can all be used to implement the ADG disaster recovery structure. Because ADG is often configured for manual switching rather than automatic switching mode.

Therefore, the efficiency of manual switching directly reflects the effect of emergency disposal!

2. Oracle ADG infrastructure deployment architecture

Take the three-tier structure of load balancing + application server + Oracle RAC (ADG) as an example, the infrastructure is shown in the following figure.

When there is a problem with the OracleRAC main library, switch to the ADG library through failover and continue to provide services.

But only one failover command is not enough, because in the process, the address of the database external service has been changed, from the original main database address IP1 to the adg address IP2.

At this time, in fact, the front-end application server connected to the database is invalid, unable to provide normal services.

For the address of the database, change or unchanged, the corresponding changes in architectural planning, the following one by one.

3. Changes in architectural planning and applicable scenarios

Change 1 the last RAC address and the ADG service address are in the same network segment.

Operation idea of emergency disposal

Failover switches to adg library

Modify the ADG library IP2 to the main library address IP1

Verify whether the business is restored

Note that in this case, if the application server supports reconnection, nothing needs to be done and the service will return to normal.

If the application server does not support the reconnect operation, you need to restart the application server again.

Change 2 Magi RAC and ADG are in different network segments, RAC and ADG, using the same set of application servers

Operation idea of emergency disposal

Failover switches to ADG library

Modify the application server data source to the address IP2 of the adg library

Restart the application server cluster connection to the ADG library

Verify whether the business is restored

Note that if the number of application servers is small, the restart of the application server can be completed quickly and the business can be restored.

However, if there are a large number of application servers and are in the peak period of business, then in the process of restarting the application servers one by one, the high concurrency traffic will crush the restarted application servers, resulting in that the service can never return to normal.

Change 3Jing RAC and ADG are in different network segments, and each deploy a set of application servers

Operation idea of emergency disposal

Failover switches to ADG library

Business change access address 2

Verify whether the business is restored

Note that if the number of business personnel is large, it is difficult to notify the change of access address one by one, which will affect the efficiency of disposal.

Change 4Jing RAC and ADG are located in different network segments and each deploy a set of application servers to unify the business access address with load balancer.

Operation idea of emergency disposal

Failover switches to ADG library

Change the load balancer point to the application server cluster of the ADG library

Verify whether the business is restored

Summary

The mind map is as follows

At this point, I believe you have a deeper understanding of "Oracle ADG deployment architecture, change and emergency response analysis". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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