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# Versioned Repository Schema caching‌

A Dimensions CM server pre-caches Versioned Repository Schema (VRS) data into a directory on disk. Pre-caching is automatic when a project, stream, or baseline is accessed for the first time and is sufficiently large to benefit from pre-caching.

The main benefits of data caching are improved performance when:

- Opening, or switching between, projects, streams, and baselines.

- Performing operations such as update, deliver, create baseline, create stream, and merge.

Dimensions CM administrators can perform initial pre-caching of the name store, project, or baseline structure data for the base database. For details on how to precache VRS data, see Administration.

See also Knowledgebase item S141604.

Configure VRS

To configure VRS, modify the following variables in the dm.cfg server configuration file:

Variable | Description
--- | ---
DISABLE_DM_DBCACHE | VRS data caching is enabled by default. To disable it, set this value to no: `DISABLE_DM_DBCACHE n`
DM_DBCACHE_DIR | Specifies the location of the VRS data cache on the server. Default locations: Windows: DM_DBCACHE_DIR C:\ProgramData\Micro Focus\Server\db_cache_dir\ UNIX: DM_DBCACHE_DIR %DM_ROOT%db_cache_dir/ Users who start application server processes (DMAPPSRV) must have read and write permission on the cache directory. A user can be: The pool owner if the listener pool is configured to run in proxy mode. The user group that is allowed to login when proxy mode is not in use (DM_ROOT/ dfs/listener.dat has the parameter -dont_use_proxy).

The following variables are hard-coded and cannot be changed:

Hard-coded variable | Description
--- | ---
    DM_DBCACHE_UPDATE_THRESHOLD 4096
| Specifies the number of new non-cached names/arcs loaded into a private VRS store section that trigger initial pre-caching/updating of an existing store.
    DM_DBCACHE_CLEANUP_INTERVAL 24
| Specifies the interval (in hours) the cache checks if the total file size for a base database exceeds the threshold set by the parameter DM_DBCACHE_MAXSIZE. If the threshold is exceeded, the files that have not been accessed for the longest period are deleted from the cache.
    DM_DBCACHE_MAXSIZE 4096
| Specifies the cache size threshold that triggers a cache cleanup.
    DM_DBCACHE_CLEANUP_THROTTLE 3600
| Idle timeout and client sessions can be very short. To avoid frequent, unnecessary cache cleanups, the default throttle interval controls how often a single application server process can schedule a cache cleanup (3600 seconds/1 hour). When a product is deleted via the DWP command, the application server runs a forced cache cleanup irrespective of the last cache cleanup time or interval.

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See also:

- Dimensions CM performance
- Advanced optimization techniques

https://admhelp.microfocus.com Dimensions CM 8942
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