Monitoring disk I/O
There are several issues you should consider to determine your course of action when you are monitoring disk I/O.
- Find the most active files, file systems, and logical volumes:
- Can "hot" file systems be better located on the physical drive or be spread across multiple physical drives? (lslv, iostat, filemon)
- Are "hot" files local or remote? (filemon)
- Does paging space dominate disk utilization? (vmstat, filemon)
- Is there enough memory to cache the file pages being used by running processes? (vmstat, svmon)
- Does the application perform a lot of synchronous (non-cached) file I/O?
- Determine file fragmentation:
- Are "hot" files heavily fragmented? (fileplace)
- Find the physical volume with the highest utilization:
- Is the type of drive or I/O adapter causing a bottleneck? (iostat, filemon)