Components of disk storage

The system uses several electronic components to manage the transfer of data from a disk to main storage. Data and programs must be in main storage before they can be used. This figure shows the hardware that is used for data transfer.
Figure shows the hardware elements used for data transfer: the processor communicates with main storage. The bus communicates with both the processor and main storage. The bus is attached to two separate IOPs, that are attached to two IOAs, that are finally attached to two disk units

Start of changeThis figure shows the hardware that is used for data transfer with a system that does not have an IOP.End of change


Figure shows the hardware elements used for data transfer: the processor communicates with main storage. The bus communicates with both the processor and main storage. The bus is attached to two separate IOAs, that are finally attached to two disk units
Bus:
The bus is the main communications channel for input and output data transfer. A system may have one or more buses.
I/O processor:
The input/output processor (IOP) is attached to the bus. The IOP is used to transfer information between main storage and specific groups of IOAs. Some IOPs are dedicated to specific types of IOAs, such as storage IOAs. Other IOPs can attach to more than one type of IOA, for example, communication IOAs and storage IOAs.
Input-output adapter (IOA):
The IOA attaches to the IOP and handles the information transfer between the IOP and the disk units.
Disk unit:
Disk units are the actual devices that contain the storage units. You order hardware at the disk-unit level. Each disk unit has a unique serial number.

The server accesses a disk unit by way of a logical address. The logical address consists of a system bus, a system card, an I/O bus, an I/O processor, an I/O adapter, I/O bus, and a device number.

To find the logical address for a disk storage component:
  1. In iSeries™ Navigator, expand My Connections (or your active environment).
  2. Expand the iSeries server you want to examine.
  3. Expand Configuration and Service.
  4. Expand Hardware.
  5. Expand Disk Units.
  6. Expand All Disk Units.
  7. Right-click a disk unit and select Properties.
Parent topic: Disk storage concepts