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Donald K. Burleson

Oracle Tips  

Oracle Database Shared between Multiple Instances

Since the instances must share locks, a lock process is started, called LCKn. In addition, the GC_ parameters must be configured in the INIT.ORA files. In Oracle8, Oracle Corporation supplies the required DLM. Under Oracle RAC, there are many changes, which we will discuss them in Chapter 14, Distributed Database Management. If the answer to the question, Will this database be shared between multiple instances?, is yes, the DBA needs to know how many instances will be sharing this database. This parameter will be used to determine INIT.ORA parameters. This answer is also important when determining the number and type of rollback segments. Rollback segments can either be private and only used by a single instance, or public and shared between all instances that access the database.

The DBA will need to know the names for all instances sharing a database. He or she should also know the number of users per instance. Figure 1.2 illustrates the concepts of shared and exclusive mode; Oracle is usually run in exclusive mode. Essentially, exclusive mode is the “normal” mode for Oracle nonshared databases.

This is an excerpt by Mike Ault’s book “Oracle Administration & Management”.  If you want more current Oracle tips by Mike Ault, check out his new book “Mike Ault’s Oracle Internals Monitoring & Tuning Scripts” or Ault’s Oracle Scripts Download.




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