Multiple instances of the database manager might be created
on a single server. This means that you can create several instances
of the same product on a physical computer, and have them running
concurrently. This provides flexibility in setting up environments.
Note: The same instance name cannot be used in two different DB2® copies.
You might want to have multiple instances to create the following
environments:
- Separate your development environment from your production environment.
- Separately tune each environment for the specific applications
it will service.
- Protect sensitive information from administrators. For example,
you might want to have your payroll database protected on its own
instance so that owners of other instances are not able to see payroll data.
Note: - On Linux or UNIX operating
systems only: To have more than one instance, the DB2 product
must be installed with root privileges. Each instance can run simultaneously, though they are
independent of the other.
- On UNIX operating systems only: To
prevent environmental conflicts between two or more instances, ensure
that each instance home directory is on a local file system.
- On Windows operating systems
only: Instances are cataloged as either local or remote in the node
directory. Your default instance is defined by the DB2INSTANCE environment
variable. You can ATTACH to other instances to
perform maintenance and utility tasks that can be done only at an
instance level, such as creating a database, forcing off applications,
monitoring a database, or updating the database manager configuration.
When you attempt to attach to an instance that is not in your default
instance, the node directory is used to determine how to communicate
with that instance.
- On any platform: DB2 database
program files are physically stored at one location and each instance
points back to the copy to which that instance belongs so that the
program files are not duplicated for each instance that is created.
Several related databases can be located within a single instance.