IBM 990 - Manual (Page 125)

Chapter 4. Channel Subsystem 113
We suggest you establish a naming convention for the logical partition identifiers. As shown
in Figure 4-2 on page 112, you could use the LCSS number concatenated to the MIF Image
ID, which means logical partition ID 3A is in LCSS 3 with MIF ID A. This fits within the allowed
range of logical partition IDs and conveys useful information to the user.
Dynamic addition or deletion of a logical partition name
In order to have a partition defined for future use, such a dynamic partition must be reserved
beforehand in the IOCDS that is used for Power-On Reset. A reserved partition is defined
with a partition name placeholder, a MIF ID, a usage type, and, optionally, may contain a
description. The reserved partition can be assigned a logical partition name to be later used
in I/O commands of HCD.
4.1.2 Physical Channel ID (PCHID)
A Physical Channel ID, or PCHID, reflects the physical identifier of a channel-type interface. A
PCHID number is based on the I/O cage location, the channel feature slot number, and the
port number of the channel feature. A CHPID does not directly correspond to a hardware
channel port on a z990, and may be arbitrarily assigned. A hardware channel is now identified
by a PCHID, or Physical Channel Identifier.
You can address 256 CHPIDs within a single Logical Channel Subsystem. That gives a
maximum of 1024 CHPIDs when four LCSSs are defined. Each CHPID is associated with a
single channel. The physical channel, which uniquely identifies a connector jack on a channel
feature, is known by its PCHID number.
PCHIDs identify the physical ports on cards located in I/O cages and follows the numbering
scheme shown in Table 4-2.
Table 4-2 PCHIDs numbering scheme
CHPIDs are not pre-assigned. It is the responsibility of the user to assign the CHPID numbers
through the use of the CHPID Mapping Tool (CMT) or HCD/IOCP. Assigning CHPIDs means
that the CHPID number is associated with a physical channel port location (PCHID), and a
LCSS. The CHPID number range is still from ‘00’ to ‘FF’ and must be unique within an LCSS.
Any CHPID not connected to a PCHIDs will fail validation when an attempt is made to build a
production IODF or an IOCDS.
A pictorial view of a z990 with multiple LCSS is shown in Figure 4-3 on page 114. Two Logical
Channel Subsystems are defined (LCSS0 & LCSS1). Each LCSS has three logical partitions
with their associated MIF Image Identifiers.
Important: Some HCD and HCM panels may still refer the user to the definition of a
“logical partition number”. For a z990 configuration, this is incorrect, and the user should
understand that the panel refers to the definition of a “MIF ID”
As previously mentioned, on a z990 the “logical partition number” is assigned by PR/SM
during Power-on Reset and cannot be modified, nor visualized, by the user.
Cage Front PCHID ## Rear PCHID ##
I/O Cage 1 100 - 1FF 200 - 2BF
I/O Cage 2 300 - 3FF 400 - 4BF
I/O Cage 3 500 - 5FF 600 - 6BF
CEC Cage 000 - 0FF reserved for ICB-4s