Synopsis

Values:100 to all buffers in the cache

Default:All buffers in the cache

Specifies the number of buffers allowed to be dirty (i.e., modified and different from what is on disk). If the number of dirty buffers in a buffer cache exceeds this value, DBWR attempts to write out buffers in order to keep the number of dirty buffers below the specified value. Note that this parameter does not impose a hard limit on the number of dirty buffers, and DBWR willnot stop or slow database activity if the number of dirty buffers exceeds this value.

DB_BLOCK_MAX_DIRTY_TARGET can be used to affect the amount of time Oracle takes to perform instance recovery, since recovery is related to the number of dirty buffers at the time of the crash. The smaller the value of this parameter, the faster the instance recovery. Note, however, that this increase in recovery time comes at the expense of writing more buffers during normal processing. Setting this parameter to a very small value might impair performance if the workload modifies large numbers of buffers. Setting this value to disables writing of buffers for incremental checkpointing purposes; all other write activity continues normally (in other words, it is unaffected by setting this parameter to 0).