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AIX operating system

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AIX operating system

"AIX" redirects here. For other uses, see AIX (disambiguation).
developer IBM
Programmed in C
OS family Unix
Working state Current
Source model Closed source
Initial release 1986
Latest stable release 7.1 TL2 / November 9, 2012; 20 months ago (2012-11-09)
Marketing target Workstation, Server
Available language(s) English
Available programming languages(s) C
Supported platforms ROMP, IBM POWER, PowerPC, IBM PS/2, System/370, ESA/390
Kernel type Dynamic Extendable
Default user interface Common Desktop Environment,
(Plasma Workspaces and GNOME optional)
License Proprietary
Official website

AIX (Advanced Interactive eXecutive, pronounced /ˌˈɛks/[1]) is a series of proprietary Unix operating systems developed and sold by IBM for several of its computer platforms. Originally released for the IBM 6150 RISC workstation, AIX now supports or has supported a wide variety of hardware platforms, including the IBM RS/6000 series and later POWER and PowerPC-based systems, IBM System i, System/370 mainframes, PS/2 personal computers, and the Apple Network Server. AIX is based on UNIX System V with 4.3BSD-compatible extensions. It is one of four commercial operating systems that are presently certified to The Open Group's UNIX 03 standard. (The others are Mac OS X, Solaris and HP-UX.)[2]

The AIX family of operating systems debuted in 1986, became the standard operating system for the RS/6000 series on its launch in 1990, and is still actively developed by IBM. It is currently supported on IBM Power Systems alongside IBM i and Linux. AIX was the first operating system to utilize journaling file systems, and IBM has continuously enhanced the software with features like processor, disk and network virtualization, dynamic hardware resource allocation (including fractional processor units), and reliability engineering ported from its mainframe designs.[3]


AIX Version 1, introduced in 1986 for the IBM 6150 RT workstation, was based on UNIX System V Releases 1 and 2. In developing AIX, IBM and Interactive Systems Corporation (whom IBM contracted) also incorporated source code from 4.2 and 4.3 BSD UNIX.

Among other variants, IBM later produced AIX Version 3 (also known as AIX/6000), based on System V Release 3, for their POWER-based RS/6000 platform. Since 1990, AIX has served as the primary operating system for the RS/6000 series (later renamed IBM eServer pSeries, then IBM System p, and now IBM Power Systems). AIX Version 4, introduced in 1994, added symmetric multiprocessing with the introduction of the first RS/6000 SMP servers and continued to evolve through the 1990s, culminating with AIX 4.3.3 in 1999. Version 4.1, in a slightly modified form, was also the standard operating system for the Apple Network Server systems sold by Apple Computer to complement the Macintosh line.

In the late 1990s, under Project Monterey, IBM and the Santa Cruz Operation planned to integrate AIX and UnixWare into a single 32-bit/64-bit multiplatform UNIX with particular emphasis on running on Intel IA-64 (Itanium) architecture CPUs. A beta test version of AIX 5L for IA-64 systems was released, but according to documents released in the SCO v. IBM lawsuit, less than forty licenses for the finished Monterey Unix were ever sold before the project was terminated in 2002.[4] In 2003, the SCO Group alleged that (among other infractions) IBM had misappropriated licensed source code from UNIX System V Release 4 for incorporation into AIX; SCO subsequently withdrew IBM's license to develop and distribute AIX. IBM maintains that their license was irrevocable, and continued to sell and support the product until the litigation was adjudicated.

AIX was a component of the 2003 SCO v. IBM lawsuit, in which the SCO Group filed a lawsuit against IBM, alleging IBM contributed SCO's intellectual property to the Linux codebase. The SCO Group, who argued they were the rightful owners of the copyrights covering the Unix operating system, attempted to revoke IBM's license to sell or distribute the AIX operating system. In March, 2010 a jury returned a verdict finding that Novell, not the SCO Group, owns the rights to Unix.[5]

AIX 6 was announced in May 2007 and ran an open beta from June 2007 until the general availability (GA) of AIX 6.1 on November 9, 2007. Major new features in AIX 6.1 included full role-based access control, workload partitions (which enable application mobility), enhanced security (Addition of AES encryption type for NFS v3 and v4) and Live Partition Mobility on the POWER6 hardware.

In April 2010, IBM published an announcement about the upcoming 7.1 release. Support is planned to continue on POWER4 or later hardware generations. Several new features, including better scalability, enhanced clustering and management capabilities are mentioned. The ability to run older versions of AIX as a WPAR keeps the opportunity to continue using 5.2 where the hardware doesn't support it. IBM intends to make 7.1 available with an Open Beta program again.[6]

Supported hardware platforms

IBM 6150 RT

The original AIX (sometimes called AIX/RT) was developed for the IBM 6150 RT workstation by IBM in conjunction with Interactive Systems Corporation, who had previously ported UNIX System III to the IBM PC for IBM as PC/IX. Installation media consisted of eight 1.2M floppy disks. The RT was based on the ROMP microprocessor, the first commercial RISC chip. This was based on a design pioneered at IBM Research (the IBM 801) .

One of the novel aspects of the RT design was the use of a microkernel, called Virtual Resource Manager (VRM). The keyboard, mouse, display, disk drives and network were all controlled by a microkernel. One could "hotkey" from one operating system to the next using the Alt-Tab key combination. Each OS in turn would get possession of the keyboard, mouse and display. Besides AIX v2, the PICK OS also utilized this microkernel.

Much of the AIX v2 kernel was written in the PL/I programming language, which proved troublesome during the migration to AIX v3. AIX v2 included full TCP/IP networking, as well as SNA and two networking file systems: NFS, licensed from Sun Microsystems, and Distributed Services (DS). DS had the distinction of being built on top of SNA, and thereby being fully compatible with DS on the IBM midrange AS/400 and mainframe systems. For the graphical user interfaces, AIX v2 came with the X10R3 and later the X10R4 and X11 versions of the X Window System from MIT, together with the Athena widget set. Compilers for Fortran and C were available. One of the more popular desktop applications was the PageMaker desktop publishing software.

IBM PS/2 series

AIX PS/2 (also known as AIX/386) was developed by Locus Computing Corporation under contract to IBM. AIX PS/2, first released in 1989, ran on IBM PS/2 personal computers with Intel 386 and compatible processors.

IBM mainframes

In 1988, IBM announced AIX/370, also developed by Locus Computing. AIX/370 was IBM's third attempt to offer Unix-like functionality for their mainframe line, specifically the System/370 (the prior versions were a TSS/370 based Unix system developed jointly with AT&T c.1980,[7] and VM/IX, a VM/370 based system developed jointly with Interactive Systems Corporation c.1984). AIX/370 was released in 1990 with functional equivalence to System V Release 2 and 4.3BSD as well as IBM enhancements. With the introduction of the ESA/390 architecture, AIX/370 was replaced by AIX/ESA in 1991, which was based on OSF/1, and also ran on the System/390 platform. This development effort was made partly to allow IBM to compete with Amdahl UTS. Unlike AIX/370, AIX/ESA ran both natively as the host operating system, and as a guest under VM. AIX/ESA, while technically advanced, had little commercial success, partially because UNIX functionality was added as an option to the existing mainframe operating system, MVS, which became MVS/ESA OpenEdition in 1999.

POWER/PowerPC-based systems

The release of AIX version 3 (sometimes called AIX/6000) coincided with the announcement of the first POWER1-based IBM RS/6000 models in 1990. The RS/6000 was unique in that it not only outperformed all other machines in integer compute performance, but also beat the competition by a factor of 10 in floating-point performance. The competition consisted of Unix workstations from the vendors Sun, HP and SGI, and, to a lesser degree, those from Intergraph and others. The machines were all roughly comparable, retailing in the $10K to $100K price range, and offering similar amounts of RAM, disk and networking, and roughly comparable graphics subsystems. The novelty of the floating-point unit was that it was tied into the integer pipeline, and performed a single multiply-add instruction per cycle (more precisely, in 3 cycles with a 3-cycle deep pipeline). The 'common wisdom' of the era was that only integer performance mattered, oddly belying the fact that many customers were running floating-point intensive numeric scientific computing workloads.

Releases of AIX version 3 also took advantage of the developments in the POWER architecture.

AIX v3 innovated in several ways on the software side. It was the first operating system to introduce the idea of a journaling file system, JFS, which allowed for fast boot times by avoiding the need to ensure the consistency of the file systems on disks (see fsck) on every reboot. Another innovation was shared libraries which avoid the need for static linking from an application to the libraries it used. The resulting smaller binaries used less of the hardware RAM to run, and used less disk space to install. Besides improving performance, it was a boon to developers: executable binaries could be in the tens of kilobytes instead of a megabyte for an executable statically linked to the C library. AIX v3 also scrapped the microkernel of AIX v2, a contentious move that resulted in v3 containing no PL/I code and being somewhat more "pure" than v2.

Other notable subsystems included:

  • IRIS GL, a 3D rendering library, the progenitor of OpenGL. IRIS GL was licensed by IBM from SGI in 1987, then still a small company which had sold only one thousand machines to date. SGI also provided the low-end graphics card for the RS/6000, capable of drawing 20,000 gouraud-shaded triangles per second. The high-end graphics card was designed by IBM, a follow-on to the mainframe-based IBM 5080, capable of rendering 990,000 vectors per second.
  • PHIGS, another 3D rendering API, popular in automotive CAD/CAM circles, and at the core of CATIA.
  • Full implementation of version 11 of the X Window System, together with Motif as the recommended widget collection and window manager.
  • Network file systems: NFS from Sun; AFS, the Andrew File System; and DFS, the Distributed File System.
  • NCS, the Network Computing System, licensed from Apollo Computer (later acquired by HP).
  • DPS on-screen display system. This was notable as a "plan B" in case the X11+Motif combination failed in the marketplace. However, it was highly proprietary, supported only by Sun, NeXT, and IBM. This cemented its failure in the marketplace in the face of the open systems challenge of X11+Motif and its lack of 3D capability.

As of 2011, AIX runs on IBM Power, System p, System i, System p5, System i5, eServer p5, eServer pSeries and eServer i5 server product lines, as well as IBM BladeCenter blades based on Power Architecture technology.[8]

POWER7 AIX Features

Performance Optimization With Enhanced RISC (POWER) version 7 enables a unique performance advantage for AIX OS. POWER7 features new capabilities using multiple cores and multiple CPU threads, creating a pool of virtual CPUs. Typically IBM POWER7 processors have eight cores with four threads per core, for a total capacity of 32 simultaneous threads or 32 virtual CPUs per processor circuit, while still using the same electricity consumption as the POWER6 processor circuit which could only support 8 virtual CPUs. AIX can harness POWER7's ability to execute instructions out-of-order instead of in-order, by using POWER7's aggressive out-of-order instruction set which drives highly efficient use of available execution paths.

AIX 7 includes a new built-in clustering capability called Cluster Aware AIX. AIX is able to organize multiple LPARs through the multipath communications channel to neighboring CPUs, enabling very high-speed communication between processors. This enables multi-terabyte memory address range and page table access to support global petabyte shared memory space for AIX POWER7 clusters so that software developers can program a cluster as if it were a single system, without using message passing (i.e. semaphore-controlled Inter-process Communication). AIX administrators can use this new capability to cluster a pool of AIX nodes. By default, AIX V7.1 pins kernel memory and includes support to allow applications to pin their kernel stack. Pinning kernel memory and the kernel stack for applications with real-time requirements can provide performance improvements by ensuring that the kernel memory and kernel stack for an application is not paged out.

AIX POWER7 systems include the Active Memory Expansion feature, which increases system flexibility where system administrators can configure logical partitions (LPARs) to use less physical memory. For example, an LPAR running AIX appears to the OS applications be configured with 80 GB of physical memory but the hardware actually only consumes 60 GB of physical memory. Active Memory Expansion employs memory compression technology to transparently compress in-memory data, allowing more data to be placed into memory and thus expanding the memory capacity of POWER7 systems. Utilizing Active Memory Expansion can improve system utilization and increase a system’s throughput. AIX 7 automatically manages the size of memory pages used to automatically use 4K, 64K or a combination of those page sizes. This self-tuning feature results in optimized performance without administrative effort.

Apple Network Servers

The Apple Network Server systems were PowerPC-based systems designed by Apple Computer to have numerous high-end features that standard Apple hardware did not have, including swappable hard drives, redundant power supplies, and external monitoring capability. These systems were more or less based on the Power Macintosh hardware available at the time but were designed to use AIX (versions 4.1.4 or 4.1.5) as their native operating system in a specialized version specific to the ANS.

AIX was only compatible with the Network Servers and was not ported to standard Power Macintosh hardware. Not to be confused is A/UX, Apple's earlier version of Unix for 68k-based Macintoshes.

IA-64 systems

As part of Project Monterey, IBM released a beta test version of AIX 5L for the IA-64 (Itanium) architecture in 2001, but this never became an official product due to lack of interest.[4]


POWER/PowerPC releases

  • AIX V7.1, Sept 10, 2010[9]
    • Support for 256 cores / 1024 threads in a single virtual machine
    • The ability to run AIX V 5.2 or V 5.3 inside of a Workload Partition
    • An XML profile based system configuration management utility
    • Support for export of Fibre Channel adapters to WPARs
    • VIOS disk support in a WPAR
    • Cluster Aware AIX
    • AIX Event infrastructure
    • Role-based access control (RBAC) with domain support for multi-tenant environments
  • AIX V6.1, November 9, 2007[10]
  • AIX 5L 5.3, August 13, 2004,[11] end of support 30 April 2012
    • NFS Version 4
    • Advanced Accounting
    • Virtual SCSI
    • Virtual Ethernet
    • Exploitation of Simultaneous multithreading (SMT)
    • Micro-Partitioning enablement
    • POWER5 exploitation
    • JFS2 quotas
    • Ability to shrink a JFS2 filesystem
    • kernel scheduler has been enhanced to dynamically increase and decrease the use of virtual processors.
  • AIX 5L 5.2, October 18, 2002,[11] end of support April 30, 2009[12]
  • AIX 5L 5.1, May 4, 2001 (Support discontinued April 1, 2006)[14]
  • AIX 4.3.3, September 17, 1999
  • AIX 4.3.2, October 23, 1998
  • AIX 4.3.1, April 24, 1998
  • AIX 4.3, October 31, 1997
  • AIX 4.2.1, April 25, 1997
    • NFS Version 3
  • AIX 4.2, May 17, 1996
  • AIX 4.1.5, November 8, 1996
  • AIX 4.1.4, October 20, 1995
  • AIX 4.1.3, July 7, 1995
  • AIX 4.1.1, October 28, 1994
  • AIX 4.1, August 12, 1994
  • AIX 4.0, 1994
    • Run on RS/6000 systems with PowerPC processors and PCI busses.
  • AIX 3.2 1992
  • AIX 3.1, February 1990
    • Journaled File System (JFS) filesystem type
  • AIX 3.0 1989
    • LVM (Logical Volume Manager) was incorporated into OSF/1, and in 1995 for HP-UX,[16] and the Linux LVM implementation is similar to the HP-UX LVM implementation.[17]
    • SMIT was introduced.

IBM PS/2 releases

  • AIX PS/2 v1.1, 1989
    • last version was 1.3, 1992.

IBM 6150 RT releases

  • AIX v2.0
    • last version was 2.2.1.
  • AIX v1.0, 1986

User interfaces

The default shell was Bourne shell up to AIX version 3, but was changed to Korn shell (ksh88) in version 4 in view of XPG4 and POSIX compliance.[18]


The Common Desktop Environment (CDE) is AIX's default graphical user interface. As part of Linux Affinity and the free AIX Toolboxes for Linux Applications (ATLA), open-source KDE Plasma Workspaces and GNOME desktop are also available.

System Management Console

SMIT is the System Management Interface Tool for AIX. It allows a user to navigate a menu hierarchy of commands, rather than using the command line. Invocation is typically achieved with the command smit. Experienced system administrators make use of the F6 function key which generates the command line that SMIT will invoke to complete it. SMIT also generates a log of commands that are performed in the smit.script file. The smit.script file automatically records the commands with the command flags and parameters used. The smit.script file can be used as an executable shell script to rerun system configuration tasks. SMIT also creates the smit.log file, which contains additional detailed information that can be used by programmers in extending the SMIT system.

smit and smitty refer to the same program, though smitty invokes the text-based version, while smit will invoke an X Window System based interface if possible; however, if smit determines that X Window System capabilities are not present, it will present the text-based version instead of failing. Determination of X Window System capabilities is typically performed by checking for the existence of the DISPLAY variable.

See also


External links

  • AIX & UNIX dW Zone
  • AIX Fix Central
  • AIX Forum
  • AIX User Groups
  • AIX Health Check
  • Submit AIX Requirements
  • AIX Toolbox for Linux Applications
  • AIX version 5.3 Documentation
  • AIX version 6.1 information center
  • AIX version 6.1 overview
  • AIX Wiki
  • AIX/ESA V2R2 General Information
  • IBM AIX page
  • IBM Systems AIX Magazine
  • IBM Electronic Service Agent
  • - Independent Portal for AIX & POWER
  • pSeriesTech.Org AIX Support Forum
  • AIX Commands, Tools, Scripts and Explanations

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