* Device: This is the device name, which can be just about anything these days. It could a volume, a volume group, a RAID array, an actual physical disk, a disk partition, or something else. The key is to first determine if Oracle is experiencing any IO response time issues. Then, in the iostat report, look for active yet poorly performing devices. If you find any, present both your Oracle and iostat analyses to your IO administrator.

* r/s: This is the number of read requests submitted to the device per second. My testing has shown reads per second correlates well with Oracle read IO operations, as determined from wait interface read wait events and also the v$filestat view's phyrds column.

* w/s: This is the number of write requests submitted to the device per second. My testing shows good write-per-second correlation with Oracle, when adding together the database writer IO operations from the v$filestat column phywrts and log writer requests from the v$sysstat statistic redo_writes. It is troubling, however, that adding all wait event write-related occurrences fell well short of the actual iostat r/s and v$filestat and v$systats numbers.