The Physical Disk performance object consists of counters that monitor hard or fixed disk drive on a computer. Disks are ...

The Physical Disk performance object consists of counters that monitor hard or fixed disk drive on a computer.  Disks are used to store file, program, and paging data and are read to retrieve these items, and written to record changes to them.  The values of physical disk counters are sums of the values of the logical disks (or partitions) into which they are divided.