ACP parameters
| Name | Attributes | Description | Default | Min | Max | Units |
|---|---|---|---|---|---|---|
| ACP_BASEPRIO | D | Sets the base priority for all ACPs. The DCL command SET PROCESS/PRIORITY can be used to reset the base priorities of individual ACPs. ACP_BASEPRIO is not applicable for XQPs. | 8 | 4 | 31 | priority |
| ACP_DATACHECK | D | Controls the consistency checks that are performed on internal file system metadata such as file headers | 2 | 0 | 99 | bitmask |
| ACP_DINDXCACHE | A,D,F | Controls the size of the directory index cache and the number of buffers used on a cachewide basis. Also, ACP_DINDXCACHE builds a temporary index into the directory file, thereby reducing search time and directory header lookup operations. | 26 | 2 | -1 | blocks |
| ACP_EXTCACHE | D,F | Sets the number of entries in the extent cache. Each entry points to one contiguous area of free space on disk. A specification of 0 means no cache. Too small a value causes excessive XQP I/O operations, while too large a value causes excessive physical memory to be consumed by the extent cache. | 64 | 0 | -1 | extents |
| ACP_EXTLIMIT | D | Specifies the maximum amount of free space to which the extent cache can point, expressed in thousandths of the currently available free blocks on the disk. For example, if available free space on the disk is 20,000 blocks, a specification of 10 limits the extent cache to 200 blocks. The computed, installed value is usually adequate. Users with four or more OpenVMS Cluster node systems might want to adjust this parameter. | 100 | 0 | 1000 | percent/10 |
| ACP_FIDCACHE | D,F | Sets the number of file identification slots cached. A specification of 1 means no cache. Too small a value causes excessive XQP I/O operations, while too large a value causes excessive physical memory to be consumed by the FID caches. | 64 | 0 | -1 | file ids |
| ACP_HDRCACHE | A,D,F | Sets the number of pages for caching file header blocks. Too small a value causes excessive XQP I/O operations, while too large a value causes excessive physical memory to be consumed by the file header caches | 36 | 8 | -1 | blocks |
| ACP_MAPCACHE | A,D,F | ACP_MAPCACHE sets the number of pages for caching index file bitmap blocks. Too small a value causes excessive XQP I/O operations, while too large a value causes excessive physical memory to be consumed by the bitmap cache. | 9 | 2 | -1 | blocks |
| ACP_MAXREAD | D | ACP_MAXREAD sets the maximum number of directory blocks read in one I/O operation | 32 | 1 | 64 | blocks |
| ACP_MULTIPLE | A,D | Enables (1) or disables (0) the default creation of a separate disk XQP cache for each volume mounted on a different device type. Prior to Version 4.0, a separate ACP process was created for each device type if this parameter was enabled. Because ACP operations are now handled by the per process XQP, such separate processes are no longer created. In general, having multiple caches is unnecessary. One large cache is more efficient than several small ones. ACP_MULTIPLE can be overridden on an individual-volume basis with the DCL command MOUNT. | 0 | 0 | 1 | boolean |
| ACP_QUOCACHE | A,D,F | Sets the number of quota file entries cached. A specification of 0 means no cache. Too small a value causes excessive XQP I/O operations, while too large a value causes excessive physical memory to be consumed by the quota caches | 64 | 0 | 2337 | users |
| ACP_REBLDSYSD | S | Specifies whether the system disk should be rebuilt if it was improperly dismounted with extent caching, file number caching, or disk quota caching enabled. The ACP_REBLDSYSD default value (1) ensures that the system disk is rebuilt. Setting the value to 0 means the disk is not rebuilt. Depending on the amount of caching enabled on the volume before it was dismounted, the rebuild operation may consume a considerable amount of time. Setting the value of ACP_REBLDSYSD to 0 specifies that the disk should be returned to active service immediately. If you set ACP_REBLDSYSD to 0, you can enter the DCL command SET VOLUME/REBUILD at any time to rebuild the disk. | 1 | 0 | 1 | boolean |
| ACP_SHARE | D | Enables (0) or disables (1) the creation of a global section for the first ACP used, enabling succeeding ACPs to share its code. This parameter should be set to 0 when ACP_MULTIPLE is on. | 1 | 0 | 1 | boolean |
| ACP_SWAPFLGS | A,D | Enables or disables swap through the value of a 4-bit number for the following four classes of ACPs: | 15 | 0 | 15 | bitmask |
| ACP_SYSACC | A,D | ACP_SYSACC sets the number of directory file control blocks (FCBs) that are cached for disks mounted with the /SYSTEM qualifier. Each directory FCB contains a 16-byte array containing the first letter of the last entry in each block of the directory (or group of blocks if the directory exceeds 16 blocks). Since entries in a directory are alphabetical, the cached FCB provides quick access to a required directory block. This parameter value should be roughly equivalent to the number of directories that are in use concurrently on each system volume. It might be overridden on a per-volume basis with the /ACCESSED qualifier to the DCL command MOUNT. The value should be kept low in systems with small physical memory and little file activity, because the FCBs require a significant amount of space in the nonpaged dynamic pool. Too small a value causes excessive XQP I/O operations, while too large a value causes excessive physical memory to be consumed by the FCB caches. | 8 | 0 | -1 | directories |
| ACP_WINDOW | D | Sets the default number of window pointers to be allocated in a window for a default file access, for disks mounted with the /SYSTEM qualifier | 7 | 1 | -1 | pointers |
| ACP_WORKSET | D | Sets the default size of a working set for an ACP. A specification of 0 permits the ACP to calculate the size. This value should be nonzero only on small systems where memory is tight. Too small a value causes excessive ACP page, while too large a value causes excessive physical memory to be consumed by the ACP. Note that this parameter has no effect on the per-process XQP | 0 | 0 | -1 | Pagelets |
| ACP_WRITEBACK | D | Controls whether deferred writes to file headers are enabled. The default value is 1, which enables deferred writes to file headers. To disable the feature, set ACP_WRITEBACK to 0. This system parameter affects only applications like PATHWORKS that can request deferred writes to file headers. Note that the deferred write feature is not available on Files-11 ODS--1 volumes | 1 | 0 | 1 | boolean |
| ACP_XQP_RES | S | Controls whether the XQP is currently in memory. The default value (1) specifies that the XQP is permanently in memory. Change the default only on restricted memory systems with a small number of users and little or no file activity that requires XQP intervention. Such activity includes file opens, closes, directory lookups, and window turns | 1 | 0 | 1 | boolean |
