If you've played around with Performance Monitor at all, you've noticed it has a few counters. And a few more. And then some. To cope with this flood of data, the counters are organized into a logical hierarchy. This hierarchy is defined by the structure of the (measurable) hardware equipment and (measurable) software elements.
At the top of the hierarchy is the Domain. Each Domain contains computers. For our purposes, each computer has distinct elements called objects. There are objects for physical components such as Processors, Physical Disks, and Memory. There are other objects, such as Process and Paging File. Each object has a set of counters defined for it. An object's counters record the activity level of the object. We use the following typographical convention to name a counter of a particular object: object: counter.
Some objects have multiple instances. For example, a computer can have multiple physical disk drives. Each such disk drive is an instance of the Physical Disk object. Each such disk drive has a name; in the case of Physical Disks it is its physical unit number. All the instances of a particular object have the same counters defined for them. The % Disk Time counter is the main indicator of how busy a disk is. Each physical disk drive has a counter that measures % Disk Time. We use the following typographical convention to denote a particular counter of an object with instances: object: counter[instance name]
This structure is used in the dialog box where you select counters for measurement. This dialog box is shown in the following section.