|Oracle9i Database Reference
Release 1 (9.0.1)
Part Number A90190-02
Initialization Parameters, 63 of 220
Spaces are not allowed within the quotation marks.
There is no default value.
|Oracle9i Real Application Clusters||
You must set this parameter for every instance, and multiple instances must have identical values. To change the value, you must shut down all instances in the cluster, change the value for each instance, and then start up each instance.
GC_FILES_TO_LOCKS is an Oracle9i Real Application Clusters parameter that has no effect on an instance running in exclusive mode. It controls the mapping of pre-release 9.0.1 parallel cache management (PCM) locks to datafiles.
One or more datafiles listed by their file numbers, or ranges of file numbers, with comma separators:
To find the correspondence between filenames and file numbers, query
FILE_ID columns of the "DBA_DATA_FILES" data dictionary view.
The number of PCM locks assigned to
file_list. By default these locks are fixed. If you set
0, then Oracle uses fine-grain locking for these files and takes locks as needed from the pool of releasable locks.
Specifies the number of contiguous blocks covered by one lock. The default is noncontiguous blocks.
Indicates that each datafile in
file_list is assigned a separate set of
lock_count PCM locks.
The value of the parameter should be set to cover as many files as possible. Therefore, to avoid performance problems, you should always change
GC_FILES_TO_LOCKS when the size of datafiles change or when new datafiles are added. Doing so requires you to shut down and restart your cluster database.
If the number of PCM locks allocated to a datafile is less than or equal to the number of blocks in a datafile, each of these locks will cover a number of contiguous blocks within the datafile equal to
blocks. If the number of PCM locks assigned to the datafile is larger than its number of blocks, resources will be wasted because some locks will not be covering any blocks.
A colon (:) separates each clause that assigns a number of PCM locks to
Oracle9i Real Application Clusters Concepts and Oracle9i Real Application Clusters Deployment and Performance for more information on setting this parameter