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IBM’S version of the UNIX Operating System is called AIX (Advanced Interactive eXecutive). 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.

The AIX operating system is designed to deliver outstanding scalability, reliability, and manageability. The AIX operating system comes from IBM, the world’s leading technology company.

IBM has broad experience in providing solutions to businesses of every size, in every industry, in every corner of the world. IBM has an excellent reputation for service and support. AIX is an open, standards-based operating system.  It provides fully integrated support for 32- and 64-bit applications.

The AIX operating system provides binary compatible support for the entire IBM UNIX product line including IBM Power Systems, System p, System i, pSeries , iSeries servers as well as the BladeCenter  blade servers.

  What is AIX?

AIX is an open operating system from IBM that is based on a version of UNIX. AIX/ESA was designed for IBM‘s System/390 or large server hardware platform. AIX/6000 is an operating system that runs on IBM‘s workstation platform, the RISC System/6000.

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 IBM POWER and PowerPC-based systems, IBM System i, System/370 mainframes, PS/2 personal computers, and the Apple Network Server


Introduced in January of 1986, AIX is the IBM implementation of the UNIX operating system. The newest version of AIX, Version 7, is binary compatible with previous versions of the AIX, including AIX 6, AIX 5L and even earlier versions of AIX. This means applications that ran on earlier versions will continue to run on AIX 7. AIX 7 is an open-standards-based UNIX OS that is designed to comply with the Open Group’s Single UNIX Specification Version 4.

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 IBM 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.

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.

AIX Evolution

Versions Of AIX

Date Version
1986 AIX 1
1987 AIX 2
1989 AIX 3
1990 AIX 3.1
1993 Sept. AIX 3.2.5
1993 AIX 4.0
1994 July AIX 4.1
1994 Oct. AIX 4.1.1, first use of the CDE desktop as AIX window desktop
1994 AIX 4.1.2
1995, June AIX 4.1.3, contains in parts of CDE 1.0
1995, Oct. AIX 4.1.4, max. file size up to 2 GByte and 2 GByte RAM, file system up to 64 GByte
1996 AIX 4.1.5, max. file size up to 2 GByte and 2 GByte RAM, file system up to 64 GByte
1996, Oct. AIX 4.2, full support of CDE 1.0, max. file size up to 64 GByte and 4 GByte RAM, file system up to 128 GByte
1994 AIX 4.2.5, BSI E3/F-C2 Security Certification
1997, Oct. AIX 4.3, BSI E3/F-C2 Security Certification
1998, April AIX 4.3.1, Certification B1/EST-X Version 2.0.1, max. file size up to 64 GByte and 16 GByte RAM, file system up to 1 TByte
1998, Oct. AIX 4.3.2, max. file size up to 64 GByte and 32 GByte RAM
1999, Sept. AIX 4.3.3, max. file size up to 64 GByte and 96 GByte RAM, file system up to 1 TByte
2000 AIX 5L
2001 May AIX 5L 5.1, up to 32 processors and 512 GByte RAM
2002 Oct. AIX 5L 5.2, up to 32 processors and 1024 GByte RAM
2004 Aug. AIX 5L 5.3, up to 64 processors and 2048 GByte RAM
2007 Juli AIX 6 OpenBeta
2007 Nov AIX 6.1
2010 AIX 7 planned

What are AIX Strengths?

  • It is based on UNIX System V and has much in common with other versions of UNIX.
  • System Management Interface Tools smit and smitty. These are very good system admin tools and cover 95% of your admin work. If you want to learn AIX command line interfaces, just hit F6 and smitty will tell you what commands it will use.
  • The IBM compilers for AIX are very good but fussy about your code. Other compilers may let you get away with ambiguous code and make assumptions, but IBM compilers will issue warning messages where your code (for example) relies on side effects or ordering that is not defined in the C standards. Initially, this is a pain but it ultimately makes the code more robust. IBM compilers cost extra.
  • Built in Logical Volume Manager (LVM) - AIX was developed from day one assuming large systems and lots of disks and so has an LVM to manage groups of disks. Some of the terms used may be different than those of other UNIX versions but the LVM is flexible, powerful, and easy to use. LVM is delivered with base AIX.
  • AIX has a Journaling Filesystem (JFS2) which supports multi-TB filesystems. The older JFS filesystem is still available, too. Both are delivered with base AIX.
  • Workload Manager (WLM) allows multiple applications to be segregated into classes and resources (CPU time, memory, and disk I/O) assigned to the classes, which allows coexistence, monitoring, and management of multiple workloads on a single OS image. (Think Solaris Containers.) WLM is delivered with base AIX.
  • HACMP - High Availability Cluster Multiprocessing allows AIX to run a cluster of machines with automated take-over and/or fail-over of applications and data between machines. HACMP is recommended for all critical solutions where minimum downtime is a requirement. HACMP is a separate product which runs on AIX.
  • Reliability, Availability and Serviceability (RAS) - marketing speak for a) things don’t break often, b) if something breaks, the machine usually either keeps running or comes back up immediately after crashing with the failing component offline, and c) the machine is usually able to identify the failing component and the failing component can often be replaced while the machine continues to run. RAS is built in to AIX and the underlying hardware. For example, POWER4 and POWER5 CPUs can sometimes detect internal errors before they become critical. AIX can then stop scheduling work to the failing CPU and take it offline while applications continue to run.
  • Logical Partitions (LPARs) - machines with POWER4 and POWER5 CPUs can be partitioned to run multiple copies of AIX (and/or Linux) at the same time. Workloads formerly run on multiple machines can be run on a single machine, allowing hardware resources to be dynamically (without reboot when running AIX V5.2, V5.3, or Linux) moved as workloads fluctuate. If workloads mesh well (encounter peak loads at different times of the day, week, month, or year), workloads consolidated onto a single machine can be run with fewer resources than required to run them on multiple separate machines, thereby reducing cost. AIX does its part to support the LPAR infrastructure and cooperate with the machine firmware, referred to as the Hypervisor.
  • Micro-partitioning - LPARs can share CPUs, which the Hypervisor time-slices. (Requires AIX V5.3 or the Linux 2.6 kernel.)
  • Virtualization – LPARs can share disks (and disk & network adapters) to reduce costs. (Requires AIX V5.3 or the Linux 2.6 kernel.)

 Getting hold of AIX

  • Most of the time AIX is supplied with a machine (OK it comes separately but is purchased with the machines) but many customers now buy machines without AIX when they intend to run Linux on POWER.
  • You can only order AIX media (usually CDs but DVD for the latest version are starting to become available), if you sign up and pay for an AIX support contract.
  • You can, however, get AIX updates via a download from the IBM Fix Central website at http://www.ibm.com/support/fixcentral/ then select: “Product Group/System p” followed by “Product/AIX” followed by the AIX release you want to update (4.3.3, 5.1, 5.2, 5.3 and 6.1) and then the appropriate “Fix Type”. You will be asked for the current level of your software and then the packages you need can be downloads. But one warning – many of these are a few hundreds of MBs, so give yourself plenty of time and space for the download.

Supported hardware platforms

AIX runs on IBM RS/6000, pSeries, p5 and System p servers. These are all the same server range with the same binary compatible CPUs under the PowerPC architecture.

1. 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) .

IBM 6150 RT

 2. 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.


3. 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.

4. 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.[citation needed] 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 (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.

Power System

5. 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. Typical IBM POWER7 processor has eight cores, and 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..


6. 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.

7. 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


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]
    • Workload Partitions (WPARs) operating system-level virtualization
    • Live Application Mobility
    • Live Partition Mobility
    • Security
      • Role Based Access Control RBAC
      • AIX Security Expert – A system and network security hardening tool
      • Encrypting JFS2 filesystem
      • Trusted AIX
      • Trusted Execution
    • Integrated Electronic Service Agent(tm) for auto error reporting
    • Concurrent Kernel Maintenance
    • Kernel exploitation of POWER6 storage keys
    • ProbeVue dynamic tracing
    • Systems Director Console for AIX
    • Integrated filesystem snapshot
    • Requires POWER4 or newer CPUs
  • 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]
    • Ability to run on the IBM BladeCenter JS20 with the PowerPC 970.
    • Minimum level required for POWER5 hardware
    • MPIO for Fibre Channel disks
    • iSCSI Initiator software
    • Participation in Dynamic LPAR
    • Concurrent I/O (CIO) feature introduced for JFS2 released in Maintenance Level 01 in May 2003[13]