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)