util_impact_lim - Instance impact policy configuration parameter

This parameter allows the database administrator (DBA) to limit the performance degradation of a throttled utility on the workload.

Configuration type
Database manager
Applies to
  • Database server with local clients
  • Database server with local and remote clients
  • Partitioned database server with local and remote clients
Parameter type
Configurable Online
Propagation class
Default [range]
10 [1 - 100 ]
Unit of measure
Percentage of allowable impact on workload

If the performance degradation is limited, the DBA can then run online utilities during critical production periods, and be guaranteed that the performance impact on production work will be within acceptable limits.

For example, a DBA specifying a util_impact_lim (impact policy) value of 10 can expect that a throttled backup invocation will not impact the workload by more than 10 percent.

If util_impact_lim is 100, no utility invocations will be throttled. In this case, the utilities can have an arbitrary (and undesirable) impact on the workload. If util_impact_lim is set to a value that is less than 100, it is possible to invoke utilities in throttled mode. To run in throttled mode, a utility must also be invoked with a non-zero priority.

Recommendation: Most users will benefit from setting util_impact_lim to a low value (for example, between 1 and 10).

A throttled utility will usually take longer to complete than an unthrottled utility. If you find that a utility is running for an excessively long time, increase the value of util_impact_lim, or disable throttling altogether by setting util_impact_lim to 100.