214 IBM Communications Server for AIX, V6: New Features and Implementation Scenarios
The latest level for all these filesets may be downloaded from the following
URL:
http://service.software.ibm.com/cgi-bin/support/rs6000.support/downloads
It is possible to have a CS/AIX configuration that does not require any fileset
to be installed:
Applications that use HPR/IP (Enterprise Extender)
Applications that use APPC over IP
U-shaped sessions (stays in the RS/6000 box)
An application that uses one of the APIs that do not leave the box such as
a NOF or CSV application
13.2 64-bit architecture and benefits
From an operation point of view, an architecture is said to be 64-bit when:
It can handle 64-bit-long data. In other words, a contiguous block of 64 bits
(8 bytes) in memory is defined as one of the elementary units that the
CPU can handle. This means that the instruction set includes instructions
for moving 64-bit-long data and instructions for performing arithmetic
operations on 64-bit-long integers.
It generates 64-bit-long addresses, both as effective addresses (the
addresses generated and used by machine instructions) and as physical
addresses (those that address the memory cards plugged into the
machine memory slots). Individual processor implementations may
generate shorter physical addresses, but the architecture must support
64-bit addresses.
The distinguishing technical features and benefits of 64-bit computing as
contrasted to 32-bit computing are:
64-bit integer computation, using hardware with 64-bit general purpose
registers
Large file support
Large application virtual address spaces
Large physical memory support
13.2.1 64-bit integer computation
Native 64-bit integer computation is provided by 64-bit hardware, and utilized
by programs computing on 64-bit data types. While there are some
Chapter 13. 64-bit SNA applications 215
specialized applications that need to do computation on integer numbers
larger than 2
32
, the key benefit of this capability is in performing arithmetic
operations on pointers in 64-bit programs. Floating point computation already
includes 64-bit precision on all RS/6000 systems.
13.2.2 Large file support
The ability to create and maintain very large file systems is increasingly
important for many users. In particular, data warehousing applications, and
scientific and multimedia applications frequently require this support.
The ability to address data in files larger that 2 GB (32-bit addresses)
requires that a program be able to specify file offsets larger than a 32-bit
number. This capability is generally considered to be a 64-bit computing
function even though it does not require 64-bit hardware support. AIX Version
4.2 provided this capability for 32-bit programs, and AIX Version 4.3 provides
it for 64-bit programs as well. Since it does not depend on 64-bit hardware,
this function can be used on any RS/6000 system running the appropriate
release of AIX.
There is, however, synergy between large file support and 64-bit hardware
capabilities, in that a 64-bit program can have much larger portions of 64-bit
files in its address space, as well as in system memory, at one time, than a
32-bit system could provide.
13.2.3 Large application virtual address spaces
In 32-bit systems, an individual program, or process, may typically have
between 2 GB and 4 GB of virtual address space for its own use to contain
instructions and data. With 64-bit computing, applications may run in a 64-bit
address space, where an individual programs addressability becomes
measured in terabytes (TB). Types of applications that currently understand
how to exploit this opportunity include the following:
Some database management programs use a large address space for
scalability, in order to maintain very large data buffers in memory, reducing
the amount of I/O they need to perform. Using a large address space, they
can supply data to client applications at the pace needed to sustain the
high transaction rate potential afforded by many of the new processors in
the industry.
In certain cases, database management programs or customer
applications may benefit from keeping an entire database or large file
immediately accessible in memory. Read-only data lends itself most

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