Extended Buffer Manager

The architecture of Extended Buffer Manager (XBM) on z/OS is designed to transparently cache DB2 data, thereby reducing I/O operations and improving performance. The core components include the XBM address space, which is the primary operational environment; buffer pools, which store the cached data; the control module, responsible for managing caching operations; and the I/O interceptor, which intercepts and redirects I/O requests. Communication between these components is primarily internal, optimized for high-speed data access.

XBM utilizes memory within the z/OS environment for its buffer pools, and it interacts with DB2 to manage data caching. The configuration of XBM involves defining buffer pool sizes, caching algorithms, and other operational parameters. These settings are managed through configuration files and modified using commands such as MODIFY.

For instance, the command MODIFY BUFFERS(size) allows dynamic adjustment of buffer pool sizes. XBM integrates with the z/OS security infrastructure, leveraging existing authentication and access control mechanisms. The system commands, such as START, STOP, and DISPLAY, are used to manage the XBM address space and monitor its status.

The I/O interceptor plays a crucial role in redirecting I/O requests to the buffer pools, ensuring transparent caching for applications. The architecture is designed for high availability and minimal overhead, ensuring that DB2 performance is enhanced without significant resource consumption.