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54 Chapter 4
Configuring and Using the 9900 Subsystem
4.2 S/390
®
Hardware Definition
4.2.1 Hardware Definition Using IOCP (MVS, VM, or VSE)
The I/O Configuration Program (IOCP) can be used to define the 9900 subsystem in MVS, VM,
and VSE environments (wherever HCD cannot be used). The 9900 subsystem supports up to
sixteen logical CU (LCU) images and 4096 LDEVs. Each LCU can hold up to 256 LDEV
addresses. An LCU is the same as an IBM
®
logical sub-system (LSS). The CUADD parameter
defines the CU images by number (0-F). The unit type can be 3990 or 2105.
Note: FICON™ support requires 2105-F20 emulation.
The following are cautions when using IOCP or HCD:
Use FEATURE=SHARE for the devices if multiple LPARs/mainframes can access the
volumes.
16,384 addresses per physical interface are allowed by MVS with FICON™ channels.
Only 1024 addresses per physical interface are allowed by MVS with ExSA™ (ESCON
®
)
channels. (This includes PAV base and alias addresses.)
Note: 4096 device addressing requires 16 CU images using CUADD=0 through CUADD=F in the
CNTLUNIT statement.
Figure 4.1 shows a sample IOCP definition for a 9900 configured with:
2105 ID.
Four FICON™ channel paths. Two channels paths are connected to a FICON™ switch. Two
channel paths are directly connected to the 9900 subsystem.
Six LCUs (0, 1, 2, 3, 4, 5) with 256 LVIs per control unit.
Sixty-four (64) base addresses and 128 alias addresses per CU 0, 1, 2, and 3.
One hundred twenty-eight (128) base addresses and 128 alias addresses per CU 4 and 5.