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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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