Initialization Parameters, 32 of 188

DB_BLOCK_MAX_DIRTY_TARGET

Parameter type:	Integer
Parameter class:	Dynamic. Scope = `ALTER SYSTEM.`
Default value:	All buffers in the cache
Range of values:	1000 to all buffers in the cache. (Setting to 0 disables limiting dirty buffers.)
Oracle Parallel Server:	Multiple instances can have different values
`DB_BLOCK_MAX_DIRTY_TARGET` specifies the number of buffers that can be dirty (modified and different from what is on disk) in the buffer cache. Therefore, it indirectly controls the duration of instance recovery by placing a rough limit on the number of blocks that must be read during crash and instance recovery.
Note: The `FAST_START_IO_TARGET` parameter (available only with Oracle Enterprise Edition) can be used to enforce a a more accurate bound on the number of I/Os during recovery.
When you specify this parameter, DBWn writes out buffers to attempt to keep the number of dirty buffers in the cache below the specified value. Setting this value to 0 disables the mechanism that limits the number of dirty buffers in the cache.
See Also: Oracle8i Designing and Tuning for Performance for more information on setting this parameter.