IBM i is an operating system that runs on IBM Power Systems and IBM PureSystems. It was named OS/400 when it was introduced with the AS/400 line of computer systems in 1988, was later renamed i5/OS, and was renamed IBM i in 2008 when IBM Power Systems was introduced.

OS familyOS/400
Working stateCurrent
Source modelClosed source
Initial release1988 (1988)
Latest release7.4 / April 23, 2019 (2019-04-23)
Marketing targetMinicomputer and enterprise server
Available inEnglish
PlatformsIBM Power Systems,
IBM PureSystems
Kernel typeshares many Microkernel (SLIC) and Virtual machine (TIMI) design philosophies
Official websiteIBM i

It is one of the operating systems supported on IBM Power Systems alongside AIX and Linux as well as on IBM PureSystems alongside AIX, Linux and Windows.


The early IBM System/36 and IBM System/38 series customers were a key target of the AS/400, so OS/400 (now known as IBM i), has built-in subsystems that provide backward compatibility with these earlier IBM general business systems. IBM i programs, like System/38 programs before them, contain both processor-independent "virtual" binary code and processor-dependent executable binary code. Compilers for IBM i produce the processor-independent code as their output; the operating system automatically translates the processor-independent code into the processor-dependent code as needed, without the need for source code or attention by IT personnel. Notably, when migrating from a legacy processor (for example, from CISC to RISC hardware), if automatic migration is configured and if the original program was created with normal options, the system will rebuild the executable code automatically and in just a few seconds. Migration consists of taking a backup from the old computer, and restoring it on the new.[1]

In 1999, IBM introduced logical partitioning (LPARs) with i5/OS to support multiple virtual systems on a single hardware footprint.

In 2014, IBM ported Node.js to IBM i.[2]

In 2018, IBM made available the Yum package manager and the capability to install open-source software via RPM packages.[3][4]


IBM designed IBM i as a "turnkey" operating system, requiring little or no on-site attention from IT staff during normal operation. For example, IBM i has a built-in DB2 database which does not require separate installation. Mass storage ("disks") can be RAID'ed or mirrored; when either of those options is configured, one or more disk can be replaced without interrupting work. System administration is wizard-driven. Automatic self-care can schedule all common system maintenance, detect many failures and order spare parts and service automatically. Organizations using IBM i sometimes have a pleasant sticker shock when comparing the overhead of cost of system maintenance on other systems.[1] The overall total cost of ownership (TCO) for IBM i on IBM Power Systems is dramatically lower than two competing platforms, like Windows/SQL Server and Linux/Oracle, primarily due to the lack of system management personnel needed; integrated components also lower the TCO.[5]

The system was one of the earliest to be object-based. Unlike traditional operating systems like Unix and Windows NT there are no files, only objects of different types. The objects persist in very large, flat virtual memory, called a single-level store.[1]

Management Interfaces

IBM Navigator for i is a web-based tool for administration of the system, database, Apache web server, and WebSphere Application Server.

IBM i Access Client Solutions is a Java-based client and a user, development and systems management interface.


IBM i also provides an environment for AIX applications to run natively on the OS without the need for an AIX LPAR.[6]

AIX programs are binary compatible with IBM i when using its PASE (Portable Applications System Environment). PASE is essentially "an operating system within an operating system", supporting the most recent stable version of AIX. Most AIX 5L compatible binaries may be executed without modification or recompilation in the PASE environment. Exceptions to this are programs that contain direct calls to AIX kernel based APIs as there is no AIX kernel in PASE. If necessary an AIX program may be built directly in PASE using a standard AIX XL C/C++ compiler, for example if native APIs are to be used. In that case APIs are provided to translate between the AIX style pointers and the native 16 byte pointers. Support is provided for running both 32-bit and 64-bit AIX executables.

Open-source software

Open-source software available includes Apache HTTP Server, OpenSSL, Java, Ruby, PHP, Python, Node.js, gcc, Nginx, Git, and much more.[7] Much of this open source software can be installed with the Yum package manager,[8] and formal support for many packages is available from IBM and partners.[9]


When IBM announced the new Power Systems line of servers on April 2, 2008, they renamed the operating system from i5/OS to IBM i[10] and changed the version identifier format from VxRxMx (Version, Release, Modification, e.g. V6R1M0) to the more standard format (e.g. 6.1).

The latest version of IBM i is 7.4, announced on April 23, 2019 and released on June 21, 2019 (Version Support Schedule).

With 7.1, IBM started delivering more updates to the operating system via Technology Refreshes. These Technology Refreshes enable further value to the operating system without the need of incurring point releases and allowing customers longer periods between upgrades. For 7.1, Technology Refresh 11 was released in October 2015. IBM i 7.2 Technology Refresh 9 was released in September 2018. IBM i 7.3 Technology Refresh 6 was released May 10, 2019.[11]

Version 7.2 was released in May 2014.[12]

Version 7.3 was released in April 2016.[13]

Version[14] Release date[15] End of Program
Old version, no longer supported: V1 1988-08-26 1993-05-31
Old version, no longer supported: V2R1 1991-05-24 1994-06-30
Old version, no longer supported: V2R1M1 1992-03-06 1994-06-30
Old version, no longer supported: V2R2 1992-12-18 1995-06-30
Old version, no longer supported: V2R3 1993-12-17 1996-05-31
Old version, no longer supported: V3R1 1995-06-21 1998-10-31
Old version, no longer supported: V3R2 1996-06-04 2000-05-31
Old version, no longer supported: V3R6 1995-12-22 1998-10-31
Old version, no longer supported: V3R7 1996-11-08 1999-06-30
Old version, no longer supported: V4R1 1997-08-29 2000-05-31
Old version, no longer supported: V4R2 1998-02-27 2000-05-31
Old version, no longer supported: V4R3 1998-09-11 2001-01-31
Old version, no longer supported: V4R4 1999-05-21 2001-05-31
Old version, no longer supported: V4R5 2000-07-28 2002-12-31
Old version, no longer supported: V5R1 2001-05-25 2005-09-30
Old version, no longer supported: V5R2 2002-08-30 2007-04-30
Old version, no longer supported: V5R3 2004-06-03 2009-04-30
Old version, no longer supported: V5R4 2007-04-20 2013-09-30
Old version, no longer supported: 6.1 2008-03-21 2015-09-30
Old version, no longer supported: 7.1 2010-04-23 2018-04-30
Older version, yet still supported: 7.2 2014-11-11 2021-04-30
Older version, yet still supported: 7.3 2016-04-15 TBA
Current stable version: 7.4 2019-06-21 TBA
Old version
Older version, still supported
Latest version
Latest preview version
Future release

See also

User groups

User groups have played a major part in the evolution of IBM i. COMMON is the world’s largest professional association of IBM technology users. It provides independent education, certification, advocacy and networking among users, IBM and related third-party solution providers.[17] The Large User Group (LUG),[18] whose membership consists of major corporations, is a major influence for current and future development of IBM i. Both COMMON and LUG work with IBM regularly to help provide constructive feedback and perspective to IBM i platform direction. The Young i Professionals (YIPS)[19] is a subset of COMMON that has been significant in influencing the direction of the IBM i.


  1. Soltis, Frank, "Inside the AS/400"; Frank Soltis was the AS/400 system architect.
  2. "Node.js". IBM i Technology Updates - Open Source Technologies.
  3. "Open Source Has Never Tasted So Good!". IBM Systems Mangazine - Open Your i.
  4. "IBM i Open Source using yum". IBM i Open Source.
  5. "IBM i's TCO Advantage Widens, According to Reports". IT Jungle.
  6. "IBM PASE for i". IBM.
  7. "IBM i Open Source using yum". IBM i Open Source.
  8. "Bitbucket". Retrieved 2019-11-18.
  9. "Open Source Support for IBM i". 2019-05-30. Retrieved 2019-11-18.
  10. IBM Introduces the First in a New Generation of Power Systems
  11. "IBM i Technology Refresh". IBM.
  12. "Planned Availability Date". IBM i 7.2 TR3 and IBM i 7.1 TR11 offer performance, usability, and integration enhancements.
  13. "IBM i 7.3". IBM i 7.3 can deliver significant client value for database and security, and support for industry-leading workloads like analytics and mobile computing.
  14. IBM i Technology Updates
  15. IBM i Software lifecycle
  16. IBM i Upgrade planning:Releases
  17. "COMMON". COMMON. Retrieved 2013-11-13.
  18. "LUG". LUG. Retrieved September 6, 2019.
  19. "Young i Professionals (YIPS)". YIPS. Retrieved 2013-11-13.
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