CPU paused for disk can be caused by poor data locality and means that the CPU had to wait instead of work. Figure 5 indicates the breakdown of the three performance zones. Pause for disk ranging above the 5 percent can also indicate a memory bottleneck. For example, make sure that your detail and master sets are on separate disk drives. Checking file structures for inefficiencies improves data locality within databases.
File fragmentation occurs when a file's set of extents becomes physically disassociated.
Fragmentation can be addressed by doing a system reload or by running defragmentation software. Memory Main memory is used by the CPU as a scratchpad or workbench. If any work is to be performed, components of that work program code and data must be resident in main memory. The fabulous 9xx systems perform very well with ample memory, but are virtually crippled by a memory shortage. HPPA systems were designed with large amounts of memory in mind.