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Wednesday, December 16, 2009

SAP Memory Types :: Roll Area

 

The roll area is a memory area with a set (configurable) size that belongs to a work process. It is located in the heap of the virtual address space of the work process.

iSeries:

the roll area is a fixed-size (configurable) area of memory situated in the shared memory in the virtual address space of the work processes.

When the context of a work process changes, the data is copied from the roll area to a common resource called the roll file. To prevent repeated copying, another roll buffer is located in between that is part of the shared memory.

iSeries:

if the context changes, quick mapping operations are performed that make the current shared memory segment in the work process available.
The roll area consists of 2 segments. The first segment, which can be set with the parameter ztta/roll_first, is assigned to the work process first as memory. If this is used up, the work process has more memory assigned to it. The amount of memory is determined by the difference between the parameters ztta/roll_area  and ztta/roll_first.
 

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