System accounting serves three important administrative functions:
- Charge-back billing (for equitable cost allocation)
- Capacity planning (to anticipate your needs)
- Resource management (to identify CPU and I/O usage)
For more information on how to identify and analyze session behavior and apply resource control, see Managing Database Resources: Operational DBAs
You may need to charge users for their use of resources. Charge-back billing permits objective cost allocation of system resources across all users.
The account string enables you to summarize resource usage by account ID. The system table DBC.Acctg tracks CPU use in seconds and I/O resources expended by a session. The I/O resource tracks the number of AMP to disk read and write operations generated by a given user or account, and charges them to the current account associated with a session.
Use the DBC.AMPUsage view to access aggregations of DBC.Acctg contents.
Resetting the Resource Usage Counters
A systems administrator can use the CPU usage information in DBC.Acctg to bill users every month. At the beginning of each month, the systems administrator runs ClearAccounting to reset the resource usage counters back to zero:
To plan for the resources needed to accommodate growth, you must know how the current workload is affecting the system. To assess the effect of the current workload, you can collect and analyze information about resource utilization.
Collecting and analyzing current resource usage information is one component of data analysis but another valuable component is the collection of historical usage statistics. The accounting feature can be used to determine the activity on current workloads, which assists you in anticipating future needs. For information on capacity planning for a new system or database, see Database Design.
You may need to control who gets specific system resources using the Workload Designer portlet in Viewpoint. For additional information, see Managing the Database Workload.