SAP Buffers
SAP Buffers
Purpose
Each SAP instance (application server) has its own buffers. These buffers are also known as client caches because they are implemented on the client, that is, the application server. SAP buffers occupy memory areas that are local to the work process, and in individual shared memory segments that can be accessed by all work processes. These memory areas are executed for the application server.
Some of the shared memory segments in an SAP System are grouped into one shared memory segment known as a pool. This is done to meet the operating system limits on the number of shared memory allocations per process. In most operating systems, you can allocate as many shared memory segments as required. The limits depend on the kernel configuration. The AIX operating system, for example, allows 10 shared memory segments per process.
SAP buffers store frequently-used data, and make this data available to the local application server instance. This helps to reduce the number of database accesses, the load on the database server (it does not need to be accessed repeatedly to obtain the same information), and network traffic. As a result, system performance is considerably improved.
The data that is buffered includes ABAP programs and screens, ABAP Dictionary data, and company-specific data. Typically these remain unchanged during system operation.
You can change, or
tune, the sizes of buffers to optimize performance for a particular hardware configuration. There are several ways to tune buffers. As there are many constraints to consider when change the buffer size, several difficulties may arise.You can use table buffering to fine-tune applications, that is, some or all of the contents of infrequently changed tables can be held in local buffers.
SAP Buffers
Program Buffer |
This buffer occupies a whole shared memory segment. |
Generic Buffer Screen Buffer |
These buffers are held in a shared memory pool. All work processes can access this pool. |
Roll Area |
Local work process buffers. Only one work process can access these buffers at a time. |
See also:
Buffer Structure Buffer Types Working with the Buffers Monitor Tuning Buffers