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In computing, a system image is a copy of the entire state of a computer system stored in some non-volatile form such as a file. A system is said to be capable of using system images if it can be shut down and later restored to exactly the same state. In such cases, system images can be used for backup.

Hibernation is an example that uses an image of the entire machine's RAM.

Disk images[edit]

Main article: Disk image

If a system has all its state written to a disk, then a system image can be produced by simply copying that disk to a file elsewhere, often with disk cloning applications. On many systems a complete system image cannot be created by a disk cloning program running within that system because information can be held outside of disks and volatile memory, for example in non-volatile memory like boot ROMs.

Process images[edit]

A process image is a copy of its state at a given point in time. It is often used for persistence. A common example is a database management system (DBMS). Most DBMS can store the state of its database or databases to a file before being closed down (see database dump). The DBMS can then be restarted later with the information in the database intact and proceed as though the software had never stopped. Another example would be the hibernate feature of many operating systems. Here, the state of all RAM memory is stored to disk, the computer is brought into an energy saving mode, then later restored to normal operation.

Some emulators provide a facility to save an image of the system being emulated. This is often called a savestate.

Programming language support[edit]

Some programming languages provide a command to take a system image of a program. This is normally a standard feature in Smalltalk (inspired by FLEX) and Lisp, among other languages. Development in these languages is often quite different from many other programming languages. For example in Lisp the programmer may load packages or other code into a running Lisp implementation using the read-eval-print loop, which usually compiles the programs. Data is loaded into the running Lisp system. The programmer may then dump a system image, containing that pre-compiled and possibly customized code - and also all loaded application data. Often this image is an executable, and can be run on other machines. This system image can be the form in which executable programs are distributed — this method has often been used by programs (such as TeX and Emacs) largely implemented in Lisp, Smalltalk, or idiosyncratic languages to avoid spending time repeating the same initialization work every time they start up.

Similar, Lisp Machines were booted from Lisp images, called Worlds. The World contains the complete operating system, its applications and its data in a single file. It was also possible to save incremental Worlds, that contain only the changes from some base World. Before saving the World, the Lisp Machine operating system could optimize the contents of memory (better memory layout, compacting data structures, sorting data, ...).

Although its purpose is different, a "system image" is often similar in structure to a core dump.

See also[edit]

External links[edit]


Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/System_image — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.

10506 news items

ITworld

ITworld
Wed, 29 Jul 2015 11:56:15 -0700

Many of us just back up our important docs, but in this case you're better off creating a system image you can recover your entire computer back to. Both Windows 7 and Windows 8 have a built-in system image creation tool (if you know where to look ...

BetaNews

BetaNews
Wed, 22 Jul 2015 08:33:45 -0700

It's aimed squarely at Windows users who don't want the hassle of discovering how to use Windows' own built-in system image tools, or who haven't made use of a third-party tool like Macrium Reflect. System GoBack Free is designed to make the process as ...

The Independent

The Independent
Tue, 28 Jul 2015 05:45:00 -0700

Windows 7, 8 and 8.1 all come with a special tool for doing so – head to Control Panel in the Start menu, choose File History and click “System Image Backup”. Follow the instructions to take an exact copy of your computer, which you can save to a hard ...

Astronomy Now Online

Astronomy Now Online
Thu, 23 Jul 2015 11:56:15 -0700

This size and scale of the Kepler-452 system compared alongside the Kepler-186 system and the solar system. Image: NASA/JPL-CalTech/R. Hurt. Interestingly, Kepler-452b provides a look into the future of our own Earth. Its star is a 'G2-type' star ...

Android Community

Android Community
Mon, 27 Jul 2015 13:37:30 -0700

This is called the “Low Effort Root” tool, and basically involves flashing a pre-rooted system image into your LG G4. That will call for the user downloading a system image file around 1.5GB in size. It's a pretty hefty download, to be sure, but ...

CNET

CNET
Fri, 24 Jul 2015 10:08:44 -0700

Both Windows 7 and Windows 8.1 come with a tool that lets you create a system image (a full backup of everything on your computer). Head to the Control Panel and select "Back up your computer" under the Systems and Security section. On the left choose ...

SuperSite for Windows

SuperSite for Windows
Wed, 15 Jul 2015 10:16:30 -0700

Here's the problem with using a disk image between dissimilar systems: A classic (Win7-style) system image contains everything that was in the original setup — user files, installed programs, the operating system itself, the system-specific drivers, etc.

CNET

CNET
Sun, 01 Mar 2015 16:56:15 -0800

One thing that's noticeably missing from the new Windows 10 Settings menu is the system image backup utility. A system image backup is basically an exact copy ("image") of a drive -- in other words, you can use a system image to completely restore your ...
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