IBM 990 - Manual (Page 69)

Chapter 2. System structure and design 57
Figure 2-15 z990 Modes of operation diagram
Logical Partitioning overview
Logical Partitioning is a function implemented by the Processor Resource/Systems Manager
(PR/SM), available on all z990 servers.
The z990 only runs in LPAR mode. This means that virtually all system aspects are now
controlled by PR/SM functions.
PR/SM is very much aware of the book structure introduced on the z990. However, logical
partitions do not have this awareness. Logical partitions have resources allocated to them
coming from a variety of physical resources, and have no control over these physical
resources from a systems standpoint—but the PR/SM functions do have.
PR/SM manages and optimizes allocation and dispatching work on the physical topology.
Most physical topology knowledge that was previously handled to the operating systems is
now the responsibility of PR/SM.
PR/SM always attempts to allocate all real storage for a logical partition within one book, and
attempts to dispatch a logical PU on a physical PU in a book that also has the central storage
for that logical partition. If not possible, a PU in an adjacent book is chosen. In general,
PR/SM tries to minimize the number of books required to allocate the resources of a given
logical partition. In addition, PR/SM always tries to re-dispatch a logical PU on the same
physical PU to assure that as much as possible of the L1 cache content can be reused.
z990
Mode
Logically
Partitioned
Mode
ESA/390 Mode
ESA/390 TPF Mode
Coupling Facility Mode
Linux Only Mode
31-bit
Architecture
Mode
64-bit
Architecture
Mode
64-bit
Architecture
Mode
31-bit
Architecture
Mode
64-bit
Architecture
Mode
TPF
CFCC
Linux on zSeries
CPs
CPs only
ICFs and/or CPs
IFLs or CPs
z/OS
Linux on zSeries
z/VSE
VSE/ESA
Linux for S/390
Operating System
Option
z/VM
OS/390 R10
Image
Modes
Linux for S/390
31-bit
Architecture
Mode
Operating
Systems
Addressing
Modes
z/VM Operating System
Option
CPs and zAAPs
(z/OS 1.6 and
above only)