## General Database Parameters

### Use

The following overview describes the general database parameters. For more information about other database parameters, see Special Database Parameters, Support Database Parameters and liveCache Database Parameters.

Changes to database parameters do not take effect until the database instance is restarted.

You can also change some database parameters while the database is running. In addition you can choose how long the change is to be effective for these database parameters:

■ Until the next restart

■ Not until after the next restart

■ Immediately and permanently

General Database Parameters (General)

Parameter | Description | How can I change this Parameter?
CACHE_SIZE | Size of the I/O buffer cache (in pages) | Changes only apply after restart
INSTANCE_TYPE | Database instance type You define the database instance type when you create the database instance and cannot change it later. | It cannot be altered.
KERNELVERSION | Version of the database software When you install a new version of the database software, the database system updates the value of this parameter. | It cannot be altered.
LOG_MIRRORED | Specifies whether the database system mirrors the log area (see Log Mode) This parameter is relevant only when you create a mirror volume with the Database Manager CLI. The Database Manager GUI automatically sets this parameter when a mirror volume is created. | Changes only apply after restart

LOG_SEGMENT_SIZE

Log segment size (in pages)

If automatic log backup is active, the database system automatically performs a log backup as soon as a log segment is full.

0: system uses 1/3 of log area as the log segment size

≤50% of the log area: system uses the value defined in LOG_SEGMENT-SIZE

> 50% of the log area: system uses 50% of the log area as the log segment size

Changes only apply after restart

MAXBACKUPDEVS | Maximum number of files or tape devices for parallel backup | Changes only apply after restart
MAXCPU | Maximum number of processors to which the database system can distribute user tasks. Note that your computer’s operating system resources have to be available for other processes as well as the database system. | Changes only apply after restart
MAXDATAVOLUMES | Maximum number of data volumes | Changes only apply after restart
MAXLOCKS | Maximum number of entries in the lock list | Changes only apply after restart
MAXLOGVOLUMES | Maximum number of log volumes | Changes only apply after restart
MAXUSERTASKS | Maximum number of simultaneously-active and therefore the maximum number of database sessions If this number has been reached, then no other user can log on to this database instance. If you choose a very high value for MAXUSERTASKS, the database system requires a lot of address space, particularly for local communication via shared memory. | Changes only apply after restart
MCOD | MCOD = Multiple Components One Database In SAP systems, indicates if other applications use the database | Changes only apply after restart
RUNDIRECTORY | Run Directory of the database instance | Changes only apply after restart

See also:

Working Memory Areas

Volumes (permanent storage)