If you use the hybrid method, update copying to the remote site is performed as described below.

• Update copying of database files is performed using asynchronous copy.
• Update copying of system files is performed using synchronous copy.

Information necessary for database recovery, such as system log files, is copied using synchronous copy to guarantee that it is imported to the remote site. Therefore, even if a disaster abnormally terminates the HiRDB system at the main site, the HiRDB system at the remote site can be restarted in the state that it was in immediately before the abnormal termination. The hybrid method is often considered the best processing method for large systems.

Recoverable database files are copied using asynchronous copy, thereby reducing the impact on transaction performance compared to using the all synchronous method.

Reference note

While the hybrid method possesses the advantages of both the all synchronous and all asynchronous methods, it is more difficult to operate than the other methods. For details about the differences in operation, see the following sections:

• 2. Points to Consider when Designing a System
• 4.2 Notes on operation when using the hybrid method
• Automatic extension of RDAREAs in Table 4-5 Operations that require the databases to be re-synchronized
• 4.2.2 Notes on initializing a database
• 6. Error Handling
• 8.7 Notes on using a shared table (applicable only to the hybrid method)

The figure below provides on overview of the hybrid method. The table below shows the processing method used for update copying to the remote site (using the hybrid method).

Figure 1-4 Overview of the hybrid method

Table 1-4 Processing method used for update copying to the remote site (using the hybrid method)

Files copied to the remote site		Processing method used for update copying
Database files		Asynchronous copy
System files	System log files	Synchronous copy
	Synchronization point dump files
	Status files