“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.
