The IOP attaches to the system I/O bus and one or more input/output
adapters (IOAs). The IOP processes instructions from the server and works
with the IOAs to control the I/O devices.
There are many different kinds of IOPs.
- Some IOPs can only support one type of I/O device. In this case the IOA
is embedded in the IOP so you can not remove the IOA or change it.
- Some IOPs can support multiple device types, but only one at a time. The
type of IOA that is attached determines what device you can use. IOAs on these
IOPs can be changed with another IOA to support a different I/O device. The
IOA and the IOP work together to control the device.
- Some IOPs can support multiple types of I/O devices at the same time.
These are known as Multifunction IOPs (MFIOP) or Combined function IOPs (CFIOP).
Multifunction IOPs connect to a variety of different IOAs. For instance, an
MFIOP could support disk units, workstations, a communications line, and removable
media devices.
- A Combined function IOP can connect to a variety of different IOAs. For
instance, a CFIOP could support disk units, a console, and communications
hardware. The CFIOP contains some of the same capabilities as an MFIOP, as
well as Ethernet and token-ring controllers. IOAs for the supported types
of I/O devices attach to the IOP.
There are several important I/O devices in the server. These include the
load source disk unit, the alternate IPL device, the system console, and the
electronic customer support hardware. The server needs to know where to locate
these special devices on secondary partitions. When you create a logical partition,
you need to identify the IOPs that control these important devices:
- The IOP that controls the disk unit that will be the load source.
- The IOP that controls the console.
- The IOP that controls the alternate IPL device.
- The IOP that controls the electronic customer support line.
Note: A system with logical partitions needs to have the correct IOP feature
codes for the load source disk unit and alternate IPL devices. Without the
correct hardware, the secondary partitions will not function correctly.
The system reports all errors that involve IOPs to the product activity
log (PAL) in the logical partition that owns the IOP. However, the system
may report errors in the PAL of the primary partition against load source
IOPs. This may occur when a secondary partition restarts.