BW 系統引數

   If  the required data is in the  R/3 buffers  on the application server, accessing them requires approximately  0.1  milliseconds  for each data record. 
      If the  data  records   are read from the database buffer, around  1  millisecond  is required.

       When the data is read from the  disk, this requires  approximately  10  milliseconds  for each data record.

Memory Allocation in SAP

An R/3 work process allocates around 5 MB of memory.

The R/3 table buffers allocate approximately 120 MB (40 MB for single record buffers, 80 MB for generic table buffers).

The data buffers of the database use around 500 MB of memory. The database on the disks can reach a size of several terabytes.

The data transfer between front end and application server occurs in blocks of 2 KB.

The transfer between application server and database server occurs in blocks of up to 32   KB.