UNIX is a computer operating system originally developed in the 1960s and 1970s by a group of AT&T employees at Bell Labs including Dennis Ritchie, Ken Thompson, and Douglas McIlroy. Today’s UNIX systems are split into various branches, developed over time by AT & T, as well as various commercial vendors and non-profit organizations.
The actual owner of the trademark UNIX is The Open Group, and industry standard consortium. Only systems fully compliant with and certified to the Single UNIX specification qualify as “UNIX” (others are called “UNIX system-like) or “UNIX-like”).
UNIX’s influence in academic circles led to large-scale adoption (particularly of the BSD variant, originating from the University of California, Berkeley) of UNIX by commercial startups, the most notable of which is SUN Microsystems.
UNIX-like operating systems such as Linux and Mac OS X are commonly encountered. Traditional UNIX may be used, sometimes, to describe a UNIX or an operating system that has the characteristics of either UNIX System V or Version seven.
The Common API Specification project started when several vendors (Sun Microsystems, IBM, Hewlett-Packard, Novell/USL and OSF) organized together to provide a single unified specification of the UNIX system services. By implementing a single common definition of the UNIX system services, third-party independent software vendors (ISVs) would be able to more easily deliver strategic applications on all of these vendor’s platforms at once.
The focus of this initiative is to deliver the core application used by current programs. The economic driver that initiated the project is the ease the porting of existing successful applications. While the work is led by a central group of vendors, it receives widespread support within the industry.
UNIX operating systems are widely used in both servers and workstations. The UNIX environment and the client-server program model were essential elements in the development of the Internet and the reshaping of computing as centered in networks rather that in individual computers.
UNIX was designed to be portable, multi-tasking and multi-user in a time-sharing configuration. UNIX systems are characterized by various concepts: the use of plain text for storing data; treating devices and certain types of inter-process communication (IPC) as files; a hierarchical file system; and the use of a large number of small programs that can be strung together through a command line interpreter using pipes, as opposed to using a single monolithic program that includes all of the same functionality. These concepts are known as the UNIX philosophy.
The operating system consists of many of these utilities along with the master control program, the kernel. Its provides services to start and stop programs, handle the file system and other common high level tasks that most programs share, and, perhaps most importantly, schedules access to hardware to avoid conflicts if two programs attempt to simultaneously access to the same resource or device. In order to mediate such access, the kernel was given with special rights on the same system and led to the division between user space and kernel space.
The microkernel tried to reverse the growing size of kernels and return to a system in which most tasks would be completed by smaller utilities. In an era when normal computer consisted of a hard disk for storage and a data terminal for input and output the UNIX file model worked quite well as most Input / Output was linear.
However, modern systems include networking and other new devices. Describing a graphical user interface driven by mouse control in an “even driven” fashion didn’t work well under the old model. Work on systems supporting these new devices led to facilities for non-blocking I/ O, forms of inter-process communications other that just pipes, as well as moving functionality such as network protocols out of the kernel.
In 2000, SCO sold its entire UNIX business and assets to Caldera Systems, which later on changed its name in the SCO Group. The new player started legal action against users and vendors of Linux. Linux contains copyrighted UNIX code now owned by The SCO Group. Other allegations include trade-secret violations by IBM, or contract violations by former Santa Cruz customers who have converted to Linux. There is a dispute with Novel, resulted in the SCO v. Novell lawsuit.
In 2005, Sun Microsystems released the bulk of its Solaris system code (based on UNIX System V release 4) into an open source project called Open Solaris. New Sun OS technologies such as the ZFS file system are now first released as open source code via Open Solaris project; as of 2006 it has spawned several non-Sun distributions such as Schilli X, Belenix, Nexenta and Martu X.
IBM admits that, just a few years ago, it held a weaker share of the UNIX market. Now IBM holds more than 25% share. It hope to grow that considerably with the POWERS line, relying on the fact that UNIX market represents more than $21 billion opportunity. It looks like while system upgrades are important for any server vendor, harnessing the added horsepower is the key and should help separate IBM from the rest of the pack. POWER chips are extending to anything from running a consumer’s games and Apple’s computers to its own servers and supercomputers, such as IBM’s.
IBM believes the evolution of the POWER architecture will ultimately yield servers that drive a true on-demand business environment for customers.
IBM is at work on AIX version 5.4, due sometime next year. While UNIX generally is good at balancing workloads across multi-CPU servers and server clusters, AIX 5.4 will take that a step further by balancing processing workloads across virtual machines.
The release will include workload management technology that came with IBM’s 2005 acquisition of Meiosys Inc. and high availability and security improvements. Customers are expected to have access to some new features. So will IBM create an open-source version of AIX along the lines of what Sun Microsystems has done with Solaris?
Hewlett-Packard updates HP-UX every two or three years, and the next release, HP-UX 11i version 3, is scheduled for the end of this year. Like IBM, HP is emphasizing improved security and high availability. HP-UX 11i v3 will offer extended virtual-view and partition management capabilities and improved support for storage area networks.
HP also is migrating third party applications that ran on VMS and Tru64 UNIX-platforms it acquired in its merger with Compaq, to its HP-UX on Itanium Integrity servers, but users of those systems have dragged their feet on converting to HP-UX; about 20% of them have moved to Linux.
New capabilities are added incrementally, too. HP just added identity management to HP-UX for user authentication.
The Dot-com crash had led to significant consolidation of UNIX users as well. Of the many commercial flavors of UNIX that were born, only Solaris, HP-UX and AIX are still relatively well in the market. Of these, Solaris has the most market share, and may be becoming more popular now that it is Open Source.
