“Total I/Os” reports the combined number of reads and writes to a device. The “% of total” column is the percentage of combined reads and writes for each named device as a percentage of the number of reads and writes that went to all devices.
You can use this information to check I/O distribution patterns over the disks and to make object placement decisions that can help balance disk I/O across devices. For example, does the data show that some disks are more heavily used than others? If you see that a large percentage of all I/O went to a specific named device, you can investigate the tables residing on the device and then determine how to remedy the problem.
See “Creating objects on segments” on page 96 in Performance and Tuning: Basics.
