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How the IOM Is Organized
5–2 7017 6300–005
How the IOM Is Organized
The IOM manages the I/O channels connected via the channel service (CS) busses and
transfers data and control information to and from main storage via the memory interface.
Each domain contains an IOM system.
IOM Logical Organization
Each IOM consists of two board types:
• Input/Output Bridge (IOB) for NX5820 or KIUB for NX5820 K which provides
connectivity between the system memory and the I/O bus.
• Common Input/Output Module
− Each CIOM comes with four channel manager facility (CMFs) which provides four
CS-bus interfaces, one CS-bus per CMF.
− In addition, the first CIOM of each domain allows two of it's four CS busses to be
directed to the backplane to drive the internal channels. These same two CS-
busses can also drive external channels.
− For NX5820, one CIOM of each domain is dedicated for IOU functionality. No
CMFs are available for CS-bus interfaces on this CIOM. Current NX5820 systems
will only support four usable CIOMs per domain for CS-bus connectivity.
− NX5820 K systems will support five usable CIOMs per domain for CS-bus
connectivity. Optionally, one CIOM in domain 0 is dedicated for Multi IOU
functionally, and one CIOM in domain 1 is dedicated for TCU functionally. These
two CIOMs can not support CS-bus connectivity.
Figure 5–1 shows the over view of the IOM organization for the NX5820. Figure 5–2 shows
the over view of the IOM organization for the NX5820 K.
0710
MSM
IOB
CIOM
IOM
*
*
2 of 4 busses can drive Internal and External Channels.
Domain 0 Domain 1
CIOMCIOM
4 CSBs
4 CSBs
**
MSM
Dedicated CIOM for IOU functionality.
**
CIOM
4 CSBs
IOB
CIOM
IOM
*
CIOMCIOM
4 CSBs
4 CSBs
CIOM
4 CSBs
CIOM
**
CIOM
4 CSBs
4 CSBs
Figure 5–1. NX5820 IOM Organization