Input/output expansion units provide additional I/O slots.
Some I/O expansion units also provide additional disk and removable
media slots.
Input/output (I/O) expansion units are connected to system units
with 12X cables and system power control network (SPCN) cables. The
12X cables can transport data and control information. The SPCN cables
can only transport control information.
The 12X cables from an I/O expansion unit connect to a 12X cable
port pair (also called a connector pair) at the system unit. The 12X
port pair is either on a pluggable card that is installed in the system
unit or mounted directly on the system unit chassis. In either case,
the connectors are wired to an I/O hub chip that drives the 12X protocol.
The pluggable cards are referred to as GX adapters or GX cards.
The 12X interconnection between I/O expansion units and system
units can be single data rate (SDR) or double data rate (DDR). Some
I/O expansion units are capable of SDR only. Others are capable of
both SDR and DDR. Similarly, some I/O hub chips and 12X cables are capable
of SDR only while others are capable of both SDR and DDR. In order
for a 12X interconnection between a system unit and I/O expansion
unit to run at DDR, the I/O hub chip, 12X cable, and expansion unit
must all be DDR capable. While components that are strictly SDR capable
cannot run at DDR, components that are DDR capable can be configured
by the system firmware to run at SDR if one or more of the other components
in the interconnection are strictly SDR capable.
For example, a DDR-capable I/O expansion unit that is connected
to a GX adapter that has a strictly SDR-capable I/O hub chip will be configured
to run at SDR. Similarly, a DDR-capable GX adapter that is connected
to a strictly SDR-capable I/O expansion unit will be configured to
run at SDR.
Notes: - Except where the distinction is important, a 12X cable refers
to either a 12X SDR cable or a 12X DDR cable.
- Except where the distinction is important, a GX adapter or GX
card refers to either an SDR or a DDR version.
- The terms I/O expansion unit and expansion unit are used interchangeably.
Important: - You can add your expansion units concurrently (with the server
powered on and partitions active) if you have one of the following
configurations:
- Your system is managed by an IBM® Hardware Management Console (HMC).
- Your system is not managed by an HMC, but has only one partition,
and that partition is running the IBM i operating system.
If your configuration does not permit adding expansion units
concurrently, you must power off the server to add expansion units.
- If additional GX adapters are needed to accommodate the new I/O
expansion units, refer to the instructions that came with the GX adapters
for information about how to install them. Installing GX adapters
must be done separately from installing expansion units. Depending
on your configuration, it might be necessary to power off the system
to install the GX adapters.
- Expansion units cannot be moved or relocated concurrently. If existing
expansion units must be relocated in the configuration to add the
new expansion units, complete the following tasks:
- Power off
the system.
- Physically relocate the existing expansion units.
- Power on
the system to firmware standby or firmware running state. The relocation
of the existing expansion units is complete.
- Add the new expansion units.
- Before performing any procedure that involves changes to the 12X
cabling or configuration for a system that is managed by an HMC, obtain a record that
identifies for each expansion unit which I/O buses exist in that expansion unit.
To acquire this information, perform the following steps:
- On the HMC,
select the managed system and then select the Properties task.
- Enter the following from the HMC command line:
lshwres
–r io ——rsubtype bus –m managed_system
- Improper completion of the procedure to connect expansion units
can result in unintended I/O configuration changes, including a change
to the bus numbers assigned to existing expansion units. When bus
numbers change, partition profiles cannot find existing I/O resources.
If this procedure completes with unexpected results, contact your
next level of support. Your next level of support can attempt to restore
bus numbers, provided that you obtained a record of the original configuration.
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