Linux on System z - AbsoluteAstronomy.com

Linux on System z is the collective term for the Linux

Linux

Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

operating system compiled to run on IBM mainframe

IBM mainframe

IBM mainframes are large computer systems produced by IBM from 1952 to the present. During the 1960s and 1970s, the term mainframe computer was almost synonymous with IBM products due to their marketshare...

s, especially System z machines. Other terms with the same meaning include Linux on zEnterprise 196, Linux on System z10, Linux on System z9
System z9
IBM System z9 is a line of IBM mainframe. It was announced on July 25, 2005 and the first models were available on September 16, 2005. The System z9 also marks the end of the previously used eServer zSeries naming convention, and it is the last z/Architecture 1 machine.- Background :System z9 is a...

, Linux on zSeries
ZSeries
IBM System z, or earlier IBM eServer zSeries, is a brand name designated by IBM to all its mainframe computers.In 2000, IBM rebranded the existing System/390 to IBM eServer zSeries with the e depicted in IBM's red trademarked symbol, but because no specific machine names were changed for...

, Linux/390, zLinux, z/Linux, etc.

History

Linux on System z originated as two separate efforts to port Linux to IBM's largest servers. The first effort, the "Bigfoot" project, developed by Linas Vepstas in late 1998 through early 1999, was an independent distribution and has since been abandoned. IBM published a collection of patches and additions to the Linux 2.2.13 kernel on December 18, 1999, to start today's mainline Linux on System z. Formal product announcements quickly followed in 2000, including the Integrated Facility for Linux

Integrated Facility for Linux

The Integrated Facility for Linux is an IBM mainframe processor dedicated to running the Linux operating system, with or without z/VM. IFLs are one of three types of IBM mainframe processors expressly designed to reduce software costs...

(IFL) engines. Think Blue Linux

Think Blue Linux

Think Blue Linux was a port of Linux to IBM S/390 mainframe computers, done by the Millenux subsidiary of German company ....

was an early mainframe distribution consisting mainly of Red Hat

Red Hat

Red Hat, Inc. is an S&P 500 company in the free and open source software sector, and a major Linux distribution vendor. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North Carolina with satellite offices worldwide....

packages added to the IBM kernel. Commercial Linux distributors introduced mainframe editions very quickly after the initial kernel work, and these mainframe versions have now been available for several years.

At the start of IBM's involvement, Linux patches for System z included some object code only (OCO) modules, without source code. However, currently Linux on System z is completely free software

Free software

Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...

under the GNU General Public License

GNU General Public License

The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....

Market outlook

In their 2005 "hype" report, IT industry analyst firm Gartner

Gartner

Gartner, Inc. is an information technology research and advisory firm headquartered in Stamford, Connecticut, United States. It was known as GartnerGroup until 2001....

cited Linux on System z as arguably the leading driver of Linux's adoption among businesses and governments. The expansion of Linux to the mainframe market has given Linux increased market credibility.

IBM announced in May 2006, that over 1,700 customers run Linux on their mainframes — which is a considerable number in the mainframe market.

IBM currently supports two Linux distributions, Red Hat

Red Hat Enterprise Linux

Red Hat Enterprise Linux is a Linux-based operating system developed by Red Hat and targeted toward the commercial market. Red Hat Enterprise Linux is released in server versions for x86, x86-64, Itanium, PowerPC and IBM System z, and desktop versions for x86 and x86-64...

and Novell SuSE

SUSE Linux Enterprise Server

SUSE Linux Enterprise Server is a Linux distribution supplied by SUSE and targeted at the business market. It is targeted for servers, mainframes, and workstations but can be installed on desktop computers for testing as well. New major versions are released at an interval of 3-4 years, while...

. Other notable Linux on System z distributions are Debian

Debian

Debian is a computer operating system composed of software packages released as free and open source software primarily under the GNU General Public License along with other free software licenses. Debian GNU/Linux, which includes the GNU OS tools and Linux kernel, is a popular and influential...

, Gentoo

Gentoo Linux

Gentoo Linux is a computer operating system built on top of the Linux kernel and based on the Portage package management system. It is distributed as free and open source software. Unlike a conventional software distribution, the user compiles the source code locally according to their chosen...

, Slackware

Slackware

Slackware is a free and open source Linux-based operating system. It was one of the earliest operating systems to be built on top of the Linux kernel and is the oldest currently being maintained. Slackware was created by Patrick Volkerding of Slackware Linux, Inc. in 1993...

, CentOS

CentOS

CentOS is a free operating system based on Red Hat Enterprise Linux . It exists to provide a free enterprise class computing platform and strives to maintain 100% binary compatibility with its upstream distribution...

and Fedora

Fedora (operating system)

Fedora is a RPM-based, general purpose collection of software, including an operating system based on the Linux kernel, developed by the community-supported Fedora Project and sponsored by Red Hat...

. The Linux kernel architecture designation is "s390" for 31-bit

31-bit

Perhaps the only computing architecture based on 31-bit addressing is one of computing's most famous and most profitable. In 1983, IBM introduced 31-bit addressing in the System/370-XA mainframe architecture as an upgrade to the 24-bit addressing of earlier models...

kernels and "s390x" for 64-bit

64-bit

64-bit is a word size that defines certain classes of computer architecture, buses, memory and CPUs, and by extension the software that runs on them. 64-bit CPUs have existed in supercomputers since the 1970s and in RISC-based workstations and servers since the early 1990s...

kernels.

Virtualization

Linux is not emulated on a mainframe. It runs as a complete native operating system, like other mainframe operating systems, at full speed using mainframe processor instructions. Thus, in its simplest configuration, a single instance of Linux can technically occupy a whole mainframe. This configuration is uncommon and not often economically sensible. IBM System z servers can run mixed workloads, including numerous other operating systems, through the use of virtualization

Full virtualization

In computer science, full virtualization is a virtualization technique used to provide a certain kind of virtual machine environment, namely, one that is a complete simulation of the underlying hardware...

. Both hardware and software co-evolved over decades to support these workloads.

System z mainframes are capable of multiple levels of virtualization. In the first level of virtualization, a single machine can be divided into as many as 60 logical partitions (LPARs), and each LPAR

LPAR

A logical partition, commonly called an LPAR, is a subset of computer's hardware resources, virtualized as a separate computer. In effect, a physical machine can be partitioned into multiple logical partitions, each hosting a separate operating system....

is a separate virtual machine running a separate operating system (OS). LPARs are implemented in hardware using a feature called PR/SM

PR/SM

PR/SM is a type-1 Hypervisor that allows multiple logical partitions to share physical resources such as CPUs, I/O channels and direct access storage devices...

which can (optionally, typically) dynamically adjust LPAR boundaries according to real-time demands. This hardware feature is always active in modern mainframes, even in the simplest configuration with a single LPAR spanning the entire machine.

Most Linux on System z customers take advantage of an additional virtualization level, z/VM

Z/VM

z/VM is the current version in IBM's VM family of virtual machine operating systems. z/VM was first released in October 2000 and remains in active use and development . It is directly based on technology and concepts dating back to the 1960s, with IBM's CP/CMS on the IBM System/360-67...

. This is a mainframe OS with a long history, and one of its main functions is a hypervisor

Hypervisor

In computing, a hypervisor, also called virtual machine manager , is one of many hardware virtualization techniques that allow multiple operating systems, termed guests, to run concurrently on a host computer. It is so named because it is conceptually one level higher than a supervisory program...

, a provider and manager of virtual machines. Operating systems, such as Linux, that run within a z/VM virtual machine are called guests or images. z/VM virtualizes not only processors and memory but also mainframe (ESCON

ESCON

ESCON is a data connection created by IBM, and is commonly used to connect their mainframe computers to peripheral devices such as disk storage and tape drives. ESCON is an optical fiber, half-duplex, serial interface. It originally operated at a rate of 10 Mbyte/s, which was later increased to...

or FICON

FICON

FICON is the IBM proprietary name for the ANSI FC-SB-3 Single-Byte Command Code Sets-3 Mapping Protocol for Fibre Channel protocol. It is a FC layer 4 protocol used to map both IBM’s antecedent channel-to-control-unit cabling infrastructure and protocol onto standard FC services and infrastructure...

) disk storage, networking, cryptographic accelerators, and other mainframe resources.

z/VM operates inside an LPAR, like any other mainframe OS. This provides two levels of Linux virtualization: based on hardware, and based on a hardware-assisted hypervisor. Moreover, z/VM can also be a guest of z/VM, creating nested levels of virtualization at any number of levels deep. Nested virtualization has extra overhead, so running z/VM as a guest is primarily used for testing purposes.

Hardware

IFLs (Integrated Facility for Linux

Integrated Facility for Linux

) are mainframe processors dedicated to running Linux, either natively or under z/VM. Microcode

Microcode

Microcode is a layer of hardware-level instructions and/or data structures involved in the implementation of higher level machine code instructions in many computers and other processors; it resides in special high-speed memory and translates machine instructions into sequences of detailed...

restricts IFLs from running "traditional" workloads, such as z/OS

Z/OS

z/OS is a 64-bit operating system for mainframe computers, produced by IBM. It derives from and is the successor to OS/390, which in turn followed a string of MVS versions.Starting with earliest:*OS/VS2 Release 2 through Release 3.8...

; they are otherwise identical to other System z processors. z/OS software vendors do not typically charge for IFL capacity, and IFLs are less expensive than general purpose engines (Central Processors, or CPs). Consequently businesses and governments can easily expand their mainframe Linux installations without affecting most of their software license charges. Although Linux can technically operate on both CPs and IFLs, IFLs simply cost less.

Linux on System z is available in both 31-bit

31-bit

and 64-bit

64-bit

versions, with the 31-bit versions rapidly losing favor as z/Architecture

Z/Architecture

z/Architecture, initially and briefly called ESA Modal Extensions , refers to IBM's 64-bit computing architecture for IBM mainframe computers. IBM introduced its first z/Architecture-based system, the zSeries Model 900, in late 2000. Later z/Architecture systems include the IBM z800, z990, z890,...

mainframes become more prevalent than the earlier ESA/390

ESA/390

ESA/390 was introduced in September 1990 and is IBM's last 31-bit-address/32-bit-data mainframe computing design, copied by Amdahl, Hitachi, and Fujitsu among other competitors...

generation. The 64-bit distributions can still run 31-bit applications. The Linux 2.6.x kernel added substantial support for mainframe hardware, such as ESCON

ESCON

, FICON

FICON

, SCSI

SCSI

Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...

-attached storage devices, and System z cryptographic accelerators. Also several vendor distributions backport

Backporting

Backporting is the action of taking a certain software modification and applying it to an older version of the software than it was initially created for. It is part of the maintenance step in a software development process....

ed 2.6.x patches to the Linux 2.4.x kernel.

Advantages

Linux on System z gives the flexibility of running Linux with the advantages of mainframe hardware. Using virtualization, numerous smaller servers can be combined onto one mainframe, gaining some benefits of centralization, but allowing specialized servers thanks to virtualization support, which can lower operating costs. IBM mainframes allow transparent use of redundant processor execution steps and integrity checking, which is necessary in the financial services industries. Mainframes typically allow hot-swapping of hardware, such as processors and memory. This swapping is typically transparent to the operating system, allowing routine repairs to be performed without shutting down the system.

When Linux applications access mainframe-based data and applications in CICS

CICS

Customer Information Control System is a transaction server that runs primarily on IBM mainframe systems under z/OS and z/VSE.CICS is a transaction manager designed for rapid, high-volume online processing. This processing is mostly interactive , but background transactions are possible...

, IBM DB2

IBM DB2

The IBM DB2 Enterprise Server Edition is a relational model database server developed by IBM. It primarily runs on Unix , Linux, IBM i , z/OS and Windows servers. DB2 also powers the different IBM InfoSphere Warehouse editions...

, IMS

Information Management System

IBM Information Management System is a joint hierarchical database and information management system with extensive transaction processing capabilities.- History :...

, and other mainframe subsystems, running on the same physical mainframe, they can utilize HiperSocket

HiperSocket

HiperSockets is an IBM technology for high-speed communications between partitions on a server with a hypervisor. The term is most commonly associated with zSeries, System z9 and System z10 mainframes which can provide in-memory TCP/IP connections between and among LPARs running several different...

s – fast, memory-only TCP/IP connections. As compared to TCP/IP over standard network interface cards (NICs, in the mainframe world called Open System Adapters, OSAs), HiperSockets can improve end-user responsiveness (reduce network latency and processing overhead), security (since there's no network connection to intercept), and reliability (since there's no network connection to lose).

Pricing and costs

Linux on System z is not appropriate for small businesses that would have fewer than about 10 distributed Linux servers, although some expensive per-processor licensed software can quickly reduce that rule of thumb

Rule of thumb

A rule of thumb is a principle with broad application that is not intended to be strictly accurate or reliable for every situation. It is an easily learned and easily applied procedure for approximately calculating or recalling some value, or for making some determination...

. Most software vendors, including IBM, treat the highly virtualized IFLs just like non-virtualized processors on other platforms for licensing purposes. In other words, a single IFL running scores of Linux instances still counts as one "ordinary" CPU, at the same CPU price, for software licensing. Test, development, quality assurance, training, and redundant production server instances can all run on one IFL (or more IFLs, but only if needed for peak demand performance capacity). Thus, beyond some minimum threshold, Linux on System z can quickly become cost-advantageous when factoring in labor and software costs.

The cost equation for Linux on System z is not always well understood and is controversial, and many businesses and governments have difficulty measuring, much less basing decisions on, software, labor, and other costs (such as the costs of outage and security breaches). Acquisition costs are often more visible, and small, non-scalable servers are "cheap." Nonetheless, non-acquisition costs are no less real and are usually far greater than hardware acquisition prices. Also, individual users and departments within larger businesses and governments sometimes have difficulty sharing computing infrastructure (or any other resources, for that matter), citing a loss of control. Server centralization, as Linux on System z provides, might reward cooperation with better service and lower costs, but that's not to say that cooperation is always easily accomplished within a corporate bureaucracy.

Linux on System z also supports less expensive disk storage devices than z/OS because Linux does not require FICON or ESCON attachment, although z/OS may use disk space more efficiently due to hardware-assisted database compression on z/OS. This compression effect is somewhat variable and may be somewhat reduced due to the minimum space allocation requirements for z/OS data set

Data set (IBM mainframe)

data set , dataset , is a computer file having a record organization. The term pertains to the IBM mainframe operating system line, starting with OS/360, and is still used by its successors, including the current z/OS. Those systems historically preferred this term over a file...

s (a full disk track).

Appropriate workloads

Mainframe characteristics are designed for such business workloads as transaction processing or large database management. Mainframe design emphasizes input/output performance, implemented via channel I/O

Channel I/O

In computer science, channel I/O is a generic term that refers to a high-performance input/output architecture that is implemented in various forms on a number of computer architectures, especially on mainframe computers...

. Historically, the principle is to offload I/O activities from the CPU as much as possible, and the z/Architecture additionally offloads cryptographic calculations. Mainframes can scale to numerous processors in a single frame, i.e. up to 64 processors in the case of the System z10 EC Model E64, which gives as much as 28.000 MIPS.

On the other hand, mainframes in general, and Linux on System z in particular, do not perform well for single task computations. Examples include most scientific simulations, weather forecasting

Weather forecasting

Weather forecasting is the application of science and technology to predict the state of the atmosphere for a given location. Human beings have attempted to predict the weather informally for millennia, and formally since the nineteenth century...

, and molecular modeling

Computational chemistry

Computational chemistry is a branch of chemistry that uses principles of computer science to assist in solving chemical problems. It uses the results of theoretical chemistry, incorporated into efficient computer programs, to calculate the structures and properties of molecules and solids...

. Supercomputers, including Linux-based supercomputers, excel at these workloads. This distinction has blurred since the introduction of the System z10, a machine based on quad-core 4.4 GHz processors with hardware decimal floating point. In this regard, the System z10 more resembles a supercomputer processor than previous mainframes.

Mainframes do not provide graphics or sound adapters, and are as such ill-suited for digital media

Digital media

Digital media is a form of electronic media where data is stored in digital form. It can refer to the technical aspect of storage and transmission Digital media is a form of electronic media where data is stored in digital (as opposed to analog) form. It can refer to the technical aspect of...

editing or computer-aided design

Computer-aided design

Computer-aided design , also known as computer-aided design and drafting , is the use of computer technology for the process of design and design-documentation. Computer Aided Drafting describes the process of drafting with a computer...

(CAD) except perhaps in support roles (e.g. content storage, parts inventories, etc.)

Support

Like all other versions of Linux, Linux on System z is governed by the GPL free software

Free software

license. Complete Linux on System z source code

Source code

In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...

is available from numerous groups on a free and equal basis, and architectural support is now part of the main Linux kernel effort. IBM assigns several of its programmers to the community effort, but IBM is by no means the only participant.

Most Linux on System z customers, particularly those with business-critical production workloads, purchase a software support contract from commercial Linux vendors such as Novell SuSE or Red Hat. IBM Global Services

IBM Global Services

IBM Global Services is the world's largest business and technology services provider. It has over 190,000 workers across more than 160 countries...

also offers support contracts, including 24x7 coverage. Some standard Linux software applications are readily available pre-compiled, including popular closed-source enterprise software packages such as WebSphere

WebSphere

IBM WebSphere refers to a brand of computer software products in the genre of enterprise software known as "application and integration middleware". These software products are used by end-users to create applications and integrate applications with other applications...

, DB2

IBM DB2

and Oracle

Oracle database

The Oracle Database is an object-relational database management system produced and marketed by Oracle Corporation....

databases and applications, SAP R/3

SAP R/3

SAP R/3 is the former name of the main enterprise resource planning software produced by SAP AG. It is an enterprise-wide information system designed to coordinate all the resources, information, and activities needed to complete business processes such as order fulfillment or billing.- History of...

, and IBM's Java

Java (programming language)

Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...

Developer's Kit (JDK), to name only a few. Nearly every free or open-source software package available for Linux generally is available for Linux on System z, including Apache HTTP Server

Apache HTTP Server

The Apache HTTP Server, commonly referred to as Apache , is web server software notable for playing a key role in the initial growth of the World Wide Web. In 2009 it became the first web server software to surpass the 100 million website milestone...

, Samba software, JBoss

JBoss

JBoss Application Server is an open-source Java EE-based application server. An important distinction for this class of software is that it not only implements a server that runs on Java, but it actually implements the Java EE part of Java...

, PostgreSQL

PostgreSQL

PostgreSQL, often simply Postgres, is an object-relational database management system available for many platforms including Linux, FreeBSD, Solaris, MS Windows and Mac OS X. It is released under the PostgreSQL License, which is an MIT-style license, and is thus free and open source software...

, MySQL

MySQL

MySQL officially, but also commonly "My Sequel") is a relational database management system that runs as a server providing multi-user access to a number of databases. It is named after developer Michael Widenius' daughter, My...

, PHP

PHP

PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...

, Python programming language

Python (programming language)

Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...

, Concurrent Versions System

Concurrent Versions System

The Concurrent Versions System , also known as the Concurrent Versioning System, is a client-server free software revision control system in the field of software development. Version control system software keeps track of all work and all changes in a set of files, and allows several developers ...

(CVS), GNU Compiler Collection

GNU Compiler Collection

The GNU Compiler Collection is a compiler system produced by the GNU Project supporting various programming languages. GCC is a key component of the GNU toolchain...

(GCC), and Perl

Perl

Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...

, among many others.

Developer resources

Linux software developers certified for System z can appeal to large enterprises and open up additional market opportunity for their products. There are few barriers to doing so as IBM offers a no-charge 30-day Linux on System z "test drive", allowing Linux developers of any size access to a live mainframe Linux guest running under z/VM for compiling and testing software. IBM also offers its Chiphopper

Chiphopper

The IBM Systems Application Advantage for Linux, also known as the Chiphopper offering, is designed to help you in porting, testing, and supporting your existing Linux® x86 applications on other IBM Systems and middleware platforms...

program to help developers write and publish cross-platform Linux software. Siebel

Siebel Systems

Siebel CRM Systems, Inc. was a software company principally engaged in the design, development, marketing, and support of customer relationship management applications. The company was founded by Thomas Siebel in 1993. At first known mainly for its sales force automation products, the company...

(now Oracle), for example, used the Chiphopper program to bring its Java-based CRM software to both Linux on System z and z/OS. The official IBM Chiphopper website provides more details about the program. Developers of open source software can make use of a community development system provided by IBM.

The developer resources can be particularly helpful for performance tuning. Performance tuning is particularly important in mainframe environments with large numbers of users. Mainframe customers tend to expect applications which can scale to high numbers of users and transactions, because that's how they use their systems every day. Sloppy programming is less tolerated, although the mainframe operating environment will keep any such programming from degrading other OS instance's performance. Some Linux application programmers do not expect this exceptional focus on code quality that the mainframe culture and mainframe operating environment demand. However, most developers quickly understand and appreciate this phenomenon, and there's a great deal of professional pride among the growing community of developers with Linux on System z experience.

Linux on System z supports Unicode

Unicode

Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...

and ASCII

ASCII

The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...

just like any other Linux distribution—it is not an EBCDIC

EBCDIC

Extended Binary Coded Decimal Interchange Code is an 8-bit character encoding used mainly on IBM mainframe and IBM midrange computer operating systems....

-based operating system. There is nothing inherent in z/Architecture that requires EBCDIC. Linux is able to read kernel parameters in EBCDIC, this ability is used in z/VM installations. Even z/OS, for that matter, supports Unicode, ASCII, and EBCDIC. Moving Linux applications to Linux on System z almost always involves just simple recompilation of the source code. The few exceptions might include source code which assumes a particular "endian" byte order or inline machine instructions for a specific processor, although these issues are not unique to Linux on System z, usually easily remedied, and quite rare.

Although programs can be easily cross compiled

Cross compiler

A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is run. Cross compiler tools are used to generate executables for embedded system or multiple platforms. It is used to compile for a platform upon which it is not feasible to...

to z/Architecture

Z/Architecture

binaries on non-mainframe Linux system, at some point such binary is usually tested either on a real mainframe, or at least on an emulated one.

Emulators

There are at least three software-based System z mainframe emulator

Emulator

In computing, an emulator is hardware or software or both that duplicates the functions of a first computer system in a different second computer system, so that the behavior of the second system closely resembles the behavior of the first system...

s. FLEX-ES from Fundamental Software is a commercially offered option. The open source Hercules emulator

Hercules emulator

Hercules is a computer emulator which allows software designed for IBM mainframe computers and for plug-compatible mainframes to run on other types of computer hardware: notably on low-cost personal computers...

supports Linux on System z (and can even run on Linux on System z itself), but IBM does not license other operating systems such as z/OS to run on Hercules. In 2010, IBM introduced the Rational Developer for System z Unit Test Feature http://www.ibm.com/software/rational/cafe/community/cobol/rdzut which provides a restricted use execution environment that can run on X86 hardware. IBM's license terms limit use of the Unit Test Feature to certain application development tasks, not including final pre-production compiling or pre-production testing (such as stress testing). The Unit Test Feature includes z/OS (with common middleware) and is also compatible with Linux on System z.

External links

Linux on System z
Linux on z/VM
Linux on System z developer site
Linux for S/390 and zSeries community wiki
linux-390, users mailing list.
linux-s390, kernel devel mailing list.
IBM Software for Linux
IBM Redbooks for Linux on System z technical know-how
IBM Redbook z/VM and Linux on IBM System z: The Virtualization Cookbook for SLES 11 SP1
IBM Redbook z/VM and Linux on IBM System z: The Virtualization Cookbook for Red Hat Enterprise Linux 6.0
Linux Technology Center at IBM
[ftp://sourceware.org/pub/gcc/summit/2003/Porting%20GCC%20to%20the%20IBM%20S390.pdf Porting GCC to the IBM S/390 platform]

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.