buffer synchronization

[Former Member]

what happens in buffer synchronization?if i need to access previous data from data base what i will do?

[Former Member]

Buffer Synchronization

The fact that each application server has its own buffers could result in data inconsistency across the various application servers (instances). To prevent data inconsistency, the SAP System uses periodical buffer synchronization, which is sometimes called buffer refresh.

Every modifying action on buffered data, which could also be buffered by other application servers, produces synchronization telegrams that are written to a central DB table (DDLOG). Every application server periodically reads the telegrams written since the last synchronization, and checks its buffers for data to be refreshed.

Buffer synchronization can be controlled by changing the following parameters in the instance profile:

rdisp/bufrefmode = sendon | sendoff, exeauto | exeoff

rdisp/bufreftime = (in seconds, time between two synchronization)

During the period between two refreshes, an application server may read data from its buffers while they are being modified by another application server. For this reason, no important volatile customer data should be buffered in the SAP buffers.

Examples of buffered data:

Table TSTC (SAP transaction codes)

Table T100 (error messages)

ABAP executables

Screens

Check this link for more..

http://help.sap.com/saphelp_nw04s/helpdata/en/c4/3a6dd5505211d189550000e829fbbd/content.htm