Informix DBA Survival Guide, Second Edition

Monitoring Disk I/O

Onstat -g iof Print Disk I/O Statistics by Chunk/File

Onstat -g iof is the onstat command that is most useful in monitoring reading and writing activity to and from the disk subsystem. Given the sensitivity of the database engine to disk access times, monitoring disk activity is of critical importance in extracting maximum performance from the IDS engine. The onstat -D command can give you similar information, but onstat -g iof is somewhat simpler and easier to understand.

This is true in OLTP systems and even more true in DSS systems. Decision support systems rely more on IDS's inherent parallelism and smart disk access to reduce the times needed for the many sequential scans that are typically seen in DSS systems. The major ...