Compatibility And Migration Considerations; Device Numbers; Multiple Subchannel Sets (Mss); Control Programs - IBM Z9 Planning Manual

Compatibility and Migration Considerations

This section provides migration and compatibility information for the System z9.

Device Numbers

When multiple systems are migrated to a System z9 CPC, the combination of
systems could include different devices or shared devices with identical device
numbers. Each system can operate in an LP without changing the device numbers
as long as identical device numbers do not occur in the same LP. However,
duplicate device numbers can exist in the same LP if these device numbers are in
different subchannel sets.
Duplicate device number conflicts can occur when the I/O configuration is
reconfigured. For example, if a reconfigurable channel path is reassigned to another
LP and devices attached to the channel path have device numbers that are already
assigned in the receiving LP to other online channel paths, a conflict results. When
IOCP generates an LPAR IOCDS, the initial configuration contains no duplicate
device number conflicts in an LP.
Device number conflicts are also detected when operator tasks change the I/O
configuration (channel path tasks from the Hardware Management Console or
support element console; or control program configuration command) or during LP
activation.
Duplicate device number conflicts are also detected when a dynamic I/O
configuration change is made.

Multiple Subchannel Sets (MSS)

A new Multiple Subchannel Sets (MSS) structure for z9 EC allows increased device
connectivity for Parallel Access Volumes (PAVs). Two subchannel sets per Logical
Channel Subsystem (LCSS) are designed to enable a total of 63.75K subchannels
in set-0 and the addition of 64K-1 subchannels in set-1. MSS, exclusive to the
System z9, is supported by ESCON (CHPID type CNC), FICON when configured as
CHPID type FC, and z/OS.

Control Programs

PTFs for supported control programs must be applied and can be obtained from the
IBM Software Support Center. A supported control program operates in an LP as it
does in one of the basic modes, with the following exceptions:

z/OS

v Physical reconfiguration, either offline or online, of CPs is not supported on the
v Physical reconfiguration, either offline or online, of central and expanded storage
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PR/SM Planning Guide
System z9. Logical CP reconfiguration, either offline or online, is supported in an
LP. This does not affect the online/offline status of the physical CPs. To
reconfigure a logical CP offline or online, use the following z/OS operator
command:
CF CPU(x),<OFFLINE/ONLINE>
is supported.
To reconfigure a central storage element offline or online, use the following z/OS
operator command:
CF STOR(E=1),<OFFLINE/ONLINE>