Diagnosis
This monitoring tree element (MTE) shows the percentage of space thathas been allocated in a buffer.

Procedure
Alerts because a buffer is full must be evaluated with care. The reason:by nature, buffers get full. SAP buffers use intelligent procedures toreplace old cached data with newly-required data. Finally, allocatingtoo much space to a buffer can cause other problems (operating systempaging) without significantly increasing the hit ratio (buffer quality).
The goal in buffer tuning is therefore to make a buffer large enough toproduce a high hit ratio with low swapping and minimal effect onoperating system paging.
Here are guidelines for deciding when to increase the size of particularSAP buffers:

• Enlarge a buffer if the swap rate (replacement of buffer objects) is
also high and/or the hit ratio is below the target threshold.

• Enlarge a buffer if there are frequent alerts in this MTE. Frequent
alerts mean that the SAP buffer displacement mechanism is not able tocreate enough free space for efficient buffer operation.

• If possible, always increase the space available to the Generic Key
buffer if it becomes full.

• The program buffer may be too small even if it still shows free space.
Enlarge the buffer or adjust the division of the buffer into sectionsfor large and small programs if the hit ratio is too low or swapping istoo high. Development systems need a larger-than-normal program buffer.

• Increasing the size of a buffer requires that you do the following:

Change the system profile parameters that size the buffer; and
Increase the size of the SAP shared memory pools in which the buffersreside. See the CCMS Guide to buffer monitoring (Help -> SAP Library ->SAP NetWeaver -> Solution Life Cycle Managment -> Solution Monitoring ->Monitoring in the CCMS -> SAP Buffers) help with these changes.

• Monitor operating system paging for significant increases and monitor
SAP memory management MTEs in case of unwanted side effects after youenlarge SAP buffers.
Background Information