Sun Performance and Tuning: Java™ and the Internet, Second Edition

Disk Workloads

There are six different basic access patterns. Read, write, and update operations can either be sequential or randomly distributed. Sequential read and write occur when files are copied and created or when large amounts of data are being processed. Random read and write can occur in indexed database reads or can be due to page-in or page-out to a file. Update consists of a read-modify-write sequence and can be caused by a database system committing a sequence of transactions in either a sequential or random pattern. When you are working to understand or improve the performance of your disk subsystem, spend some time working out which of these categories you expect to be most important.

You cannot automatically tell which processes ...