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Roll area and Paging area are two very important concepts of memory management. Roll area is a memory area with a set size that belongs to a work process. It is located in the heap of the virtual address space of the work process. Disk area (swap space) is used as an extension of the physical memory for temporary storage. When SAP tries to keep track of processes requiring more physical memory than available, then data is moved to and from the swap space. If only segments of the processes are so copied, it is called paging. This test extracts statistics specific to these two memory concepts.

Measurement	Description	Measurement Unit	Interpretation
Paging_used	The percentage utilization of the swap space (paging area)	Percent	Paging utilizes CPU resources, performs disk reads / writes, and hence is considered an expensive operation. However, paging itself occurs only when the memory is low. Therefore, if more paging area is used, it means one has to kill some processes or increase physical memory size.
Roll_used	The percentage of roll area that has been used	Percent	When the context of a work process changes, the data is copied from the roll area to a common resource called the roll file. First the process tries to occupy the roll area of the memory. When roll area is full, extended memory is used up by the process. The default value is specified in transaction RZ11, and is determined dynamically. Roll area should not be changed manually.If one has to still to make changes on one's platform, keep in mind the following dependencies: rdisp/ROLL_SHM should be adjusted if ztta/roll_area is changed rdisp/ROLL_MAXFS must be adjusted if ztta/roll_area is changed ztta/roll_area must be larger than, or the same size as ztta/roll_first