Interacting with Operating-System Resource Control

Many operating systems provide tools for resource management. These tools often contain "workload manager" or "resource manager" in their names, and are intended to allow multiple applications to share the resources of a single server, using an administrator-defined policy. Oracle Database expects a static configuration and allocates internal resources, such as latches, from available resources detected at database startup. The database might not perform optimally and can become unstable if operating system resource configuration changes frequently.

Guidelines for Using Operating-System Resource Control

If you do choose to use Operating-system resource control with Oracle Database, then you must use it judiciously, according to the following guidelines:

In general, operating system resource control should not be used concurrently with Oracle Database Resource Manager (the Resource Manager), because neither of them are aware of each other's existence. As a result, both the operating system and the Resource Manager try to control resource allocation in a manner that causes unpredictable behavior and instability of Oracle Database.
- If you want to control resource distribution within an instance, use the Resource Manager and turn off operating-system resource control.
- If you have multiple instances on a node and you want to distribute resources among them, use operating-system resource control, not the Resource Manager.
  
  Note:
  Oracle Database currently does not support the use of both tools simultaneously. Future releases might allow for their interaction on a limited scale.
If you decide to use an operating system resource manager (such as Hewlett Packard's Process Resource Manager or Sun's Solaris Resource Manager) concurrently with Oracle Database Resource Manager (the Resource Manager), you must ensure that all of the following conditions are met:
- Each database instance must be assigned to a dedicated operating-system resource manager group or managed entity.
- The dedicated entity running all the instance's processes must run at one priority (or resource consumption) level.
- The CPU resources assigned to the dedicated entity cannot be changed more frequently than once every few minutes.
- Process priority management must not be enabled.
  
  Caution:
  Management of individual database processes at different priority levels (for example, using the nice command on UNIX platforms) is not supported. Severe consequences, including instance crashes, can result. You can expect similar undesirable results if operating-system resource control is permitted to manage the memory to which an Oracle Database instance is pinned.
If you decide to use operating system resource control only, ensure that you turn off the Resource Manager. See "Disabling the Resource Manager" for instructions.