IBM 990 - Manual (Page 71)

Chapter 2. System structure and design 59
Figure 2-16 Logical processor assignment (HMC- Image Profile)
On the z990, the sum of defined and reserved logical processors for an ESA/390 mode
logical partition is limited to 32. However, z/OS 1.6 and z/VM 5.1 operating systems are
planned to support up to 24 processors. For z/OS, the 24 processors limit applies to the
sum of CPs and zAAPs logical processors. The weight and the number of online logical
processors of a logical partition can be dynamically managed by the LPAR CPU
Management function of the Intelligent Resource Director, to achieve the defined goals of
this specific partition and of the overall system.
Memory
Memory, either Central Storage or Expanded Storage, must be dedicated to a logical
partition. The defined storage(s) must be available during the logical partition activation;
otherwise, the activation fails.
Reserved storage can be defined to a logical partition, enabling non-disruptive memory
add to and removal from a logical partition, using the LPAR Dynamic Storage
Reconfiguration. Refer to 2.2.11, “LPAR Dynamic Storage Reconfiguration (DSR)” on
page 71 for more information.
Channels
Channels can be shared between logical partitions by including the partition name in the
partition list of a Channel Path ID (CHPID). I/O configurations are defined by the I/O
Configuration Program (IOCP) or the Hardware Configuration Dialog (HCD) in conjunction
with the CHPID Mapping Tool (CMT). The CMT is an optional, but strongly recommended,
tool used to map CHPIDs onto Physical Channel IDs (PCHIDs) that represent the physical
location of a port on a card in an I/O cage.