Monday, April 19, 2010

operating system



In computing, an operating system (OS) is software (programs and data) that provides an interface between the hardware and other software. The OS is responsible for management and coordination of processes and allocation and sharing of hardware resources such as RAM and disk space, and acts as a host for computing applications running on the OS. An operating system may also provide orderly accesses to the hardware by competing software routines. This relieves the application programmers from having to manage these details.
Microsoft Windows is a family of proprietary operating systems that originated as an add-on to the older MS-DOS operating system for the IBM PC. Modern versions are based on the newer Windows NT kernel that was originally intended for OS/2. Windows runs on x86, x86-64 and Itanium processors. Earlier versions also ran on the Alpha, MIPS, Fairchild (later Intergraph), Clipper and PowerPC architectures (some work was done to port it to the SPARC architecture).

As of 2009, Microsoft Windows still holds a large amount of the worldwide desktop market share. Windows is also used on servers, supporting applications such as web servers and database servers. In recent years, Microsoft has spent significant marketing and research & development money to demonstrate that Windows is capable of running any enterprise application, which has resulted in consistent price/performance records (see the TPC) and significant acceptance in the enterprise market.

Currently, the most widely used version of the Microsoft Windows family is Windows XP, released on October 25, 2001.

In November 2006, after more than five years of development work, Microsoft released Windows Vista, a major new operating system version of Microsoft Windows family which contains a large number of new features and architectural changes. Chief amongst these are a new user interface and visual style called Windows Aero, a number of new security features such as User Account Control, and a few new multimedia applications such as Windows DVD Maker. A server variant based on the same kernel, Windows Server 2008, was released in early 2008.

On October 22, 2009, Microsoft released Windows 7, the successor to Windows Vista, coming three years after its release. While Vista was about introducing new features, Windows 7 aims to streamline these and provide for a faster overall working environment. Windows Server 2008 R2, the server variant, was released at the same time.


Mac OS X supports HFS+ with journaling as its primary file system. It is derived from the Hierarchical File System of the earlier Mac OS. Mac OS X has facilities to read and write FAT, UDF, and other file systems, but cannot be installed to them. Due to its UNIX heritage Mac OS X now supports virtually all the file systems supported by the VFS.



Many GNU/Linux distributions support some or all of ext2, ext3, ext4, ReiserFS, Reiser4, JFS , XFS , GFS, GFS2, OCFS, OCFS2, and NILFS. The ext file systems, namely ext2, ext3 and ext4 are based on the original GNU/Linux file system. Others have been developed by companies to meet their specific needs, hobbyists, or adapted from UNIX, Microsoft Windows, and other operating systems. GNU/Linux has full support for XFS and JFS, along with FAT (the MS-DOS file system), and HFS which is the primary file system for the Macintosh.

In recent years support for Microsoft Windows NT's NTFS file system has appeared in GNU/Linux, and is now comparable to the support available for other native UNIX file systems. ISO 9660 and Universal Disk Format (UDF) are supported which are standard file systems used on CDs, DVDs, and BluRay discs. It is possible to install GNU/Linux on the majority of these file systems. Unlike other operating systems, GNU/Linux and UNIX allow any file system to be used regardless of the media it is stored in, whether it is a hard drive, a disc (CD,DVD...), a USB key, or even contained within a file located on another file system.



The Solaris Operating System uses UFS as its primary file system. Prior to 1998, Solaris UFS did not have logging/journaling capabilities, but over time the OS has gained this and other new data management capabilities.

Additional features include Veritas (Journaling) VxFS, QFS from Sun Microsystems, enhancements to UFS including multiterabyte support and UFS volume management included as part of the OS, and ZFS (free software, poolable, 128-bit, compressible, and error-correcting).

Kernel extensions were added to Solaris to allow for bootable Veritas VxFS operation. Logging or journaling was added to UFS in Solaris 7. Releases of Solaris 10, Solaris Express, OpenSolaris, and other open source variants of Solaris later supported bootable ZFS.

Logical Volume Management allows for spanning a file system across multiple devices for the purpose of adding redundancy, capacity, and/or throughput. Solaris includes Solaris Volume Manager (formerly known as Solstice DiskSuite.) Solaris is one of many operating systems supported by Veritas Volume Manager. Modern Solaris based operating systems eclipse the need for volume management through leveraging virtual storage pools in ZFS.

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