Physical and logical objects in HCM
The IODF contains information about logical objects and how they are defined to each other. HCM displays physical objects and their connections in the configuration diagram, and contains the logical information associated with the physical objects in dialogs. For example, a device may be logically defined to a processor; however, physically, the device may reside in a unit in a string which connects to a controller daisy-chained to another controller, leading to a series of crossbar switches which finally connect through a CHPID to the processor. The configuration diagram shows all the connected physical objects; the device <=> processor logical definition information can be found in the appropriate dialog.
The processor only needs to know the logical routing that reaches the desired device–the logical definition. As a system administrator, you need to know how the processor and device are connected–the physical configuration–as well as the logical links.
Tip
Since HCM usually makes both the physical connection and logical definitions in the same step, the logical definitions usually have corresponding physical routes. However, situations may occur where the logical definitions and physical routes do not match. HCM highlights these cases in the configuration diagram; see Receiving visual warnings for details.
In HCM, most physical objects contain logical objects (for example, cabinets do not contain logical objects, but patchports, and patchports are physical objects). A logical object is contained in a physical object and in most cases, permanently associated with it. However, an operating system is a logical object, but is not contained in a physical object. Physical and logical objects are associated during IODF Load or Resync, or when the logical object is created and added to a physical object in HCM. To identify the logical objects that are associated to a physical object, the serial numbers are a major guide. For example, when assigning control units to controllers, especially in dual mode controllers.
- For processors:
- Any multiple logical processors in the IODF which belong to the same physical processor should have the same serial number or SNA address.
- For control units:
- Control units which belong to the same controller should have the same serial number (for example, the two control units in a 3990 DASD subsystem). HCM relies on this to resolve ambiguities where other information is insufficient to make this determination.
- For devices:
- Devices which are physically in the same string should have the same serial number. If you have more than one device with the same device number, HCM uses the serial number to determine whether the devices are physically identical. Usualla, it is sufficient to assign serial numbers to just the first device in each string, as devices with the same serial number are placed in the same string. If two devices have different device numbers but the same serial number, they are considered to be in the same physical string.
See Preparing the IODF for details.