A boot image is a type of

disk image A disk image, in computing, is a computer file containing the contents and structure of a disk volume or of an entire data storage device, such as a hard disk drive, tape drive, floppy disk, optical disc, or USB flash drive. A disk image is usua ...

(a computer file containing the complete contents and structure of a

storage medium Data storage is the recording (storing) of information ( data) in a storage medium. Handwriting, phonographic recording, magnetic tape, and optical discs are all examples of storage media. Biological molecules such as RNA and DNA are cons ...

). When it is transferred onto a

boot device In computing, booting is the process of starting a computer as initiated via hardware such as a button or by a software command. After it is switched on, a computer's central processing unit (CPU) has no software in its main memory, so some ...

it allows the associated hardware to

boot A boot is a type of footwear. Most boots mainly cover the foot and the ankle, while some also cover some part of the lower calf. Some boots extend up the leg, sometimes as far as the knee or even the hip. Most boots have a heel that is clear ...

. The ''boot image'' usually includes the operating system, utilities and diagnostics, as well as boot and data recovery information. It also includes those "applications" used organization-wide. A specialized image for a particular type of user or department is called typically a departmental boot image. Building such an image can take days or weeks, and involve complex decisions about licensing and permissions - including which passwords to store in the boot image and which to require users to type in - and requires experts in

software integration System integration is defined in engineering as the process of bringing together the component sub-systems into one system (an aggregation of subsystems cooperating so that the system is able to deliver the overarching functionality) and ensuring ...

to do. However, once built, the boot image can be simply copied onto devices, patched within reasonable limits, and remains disposable in case of any problems (

viruses A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's ...

in particular). This is possible because unlike other hard drive images (which may contain any data, et al.), pure boot images contain no mission-critical data. By definition a pure boot image contains no data that cannot be reproduced from configurations or off-the-shelf executables. In particular end-user data is not part of a boot image, although some operating systems require that a copy of user preferences or configuration files be kept within the boot image itself, e.g.

Microsoft Windows Windows is a group of several Proprietary software, proprietary graphical user interface, graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, W ...

registry. Utilities like

Norton Ghost Ghost (an acronym for ''general hardware-oriented system transfer'') is a disk cloning and backup tool originally developed by Murray Haszard in 1995 for Binary Research. The technology was acquired in 1998 by Symantec. The backup and reco ...

keep a backup copy of the boot image, for quick re-imaging (often called re-installation) in the event of a problem, thus avoiding the need to diagnose a specific problem with a specific machine.

As virtual machine

Some

virtual machine In computing, a virtual machine (VM) is the virtualization/emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized har ...

infrastructure can directly import and export a boot image for direct installation to "bare metal", i.e. a disk. This is the standard technique for

OEM An original equipment manufacturer (OEM) is generally perceived as a company that produces non-aftermarket parts and equipment that may be marketed by another manufacturer. It is a common industry term recognized and used by many professional or ...

s to install identical copies of an operating system on many identical machines: The boot image is created as a virtual machine and then exported, or created on one disk and then copied via a boot image control infrastructure that also makes

copies. The

VMware vCenter Converter VMware, Inc. is an American cloud computing and virtualization technology company with headquarters in Palo Alto, California. VMware was the first commercially successful company to virtualize the x86 architecture. VMware's desktop software ru ...

for instance lets users "convert physical machines to virtual machines - for free" as part of that company's suite of products to make images easier to back up and manage. Equivalents exist for

Xen Xen (pronounced ) is a type-1 hypervisor, providing services that allow multiple computer operating systems to execute on the same computer hardware concurrently. It was originally developed by the University of Cambridge Computer Laborator ...

and other VM systems.

Goals

By keeping the boot image entirely separate and disposable, and mandating boot image control, organizations seek to keep their total cost of operations (including its

total cost of ownership Total cost of ownership (TCO) is a financial estimate intended to help buyers and owners determine the direct and indirect costs of a product or service. It is a management accounting concept that can be used in full cost accounting or even eco ...

component) low. Often such organizations look at uptime as a service. One goal of boot image control is to minimize the number of boot images used by an organization to reduce support costs. It includes at least: * Specifying the machine hardware to minimize unneeded machine diversity and minimize the resultant number of boot images. * Upgrading new machine specifications at low additional cost ensures that they will remain useful long past their normal life. Extending the life of desktop machines will reduce the incursion of off-spec machines later in the life-cycle, improving standardization, reducing support costs, minimizing e-waste. * Organizing the network so that boot images can be efficiently supported, independent of data. Data must not be dependent on

s. Use networks to store data on secure servers. * Hardware

acceptance testing In engineering and its various subdisciplines, acceptance testing is a test conducted to determine if the requirements of a specification or contract are met. It may involve chemical tests, physical tests, or performance tests. In systems ...

on each new machine confirms that it is fit for use in a standardized boot image environment. * Boot image installation to ensure that only supportable standardized boot images are used. *

Troubleshooting Troubleshooting is a form of problem solving, often applied to repair failed products or processes on a machine or a system. It is a logical, systematic search for the source of a problem in order to solve it, and make the product or process ope ...

and help desk functions employ standardized tests to identify the source of problems: boot, software, or hardware. * Desktop system recovery tools and procedures for failed desktop units. These would use backup copies of a boot image created with utilities such as

. In a large organization with many compatible machines, rapid recovery by replacing with a backup boot image may only take a few minutes, with considerable cost savings. * Data backup and recovery procedures ensure data is stored in the right place so that it can be recovered promptly in crisis situations. * Installing services for the disabled with a single boot image in a manner that is ubiquitous and cost effective, meeting the needs of all staff regardless of disability, with available technology services. *

Remote work Remote work, also called work from home (WFH), work from anywhere, telework, remote job, mobile work, and distance work is an employment arrangement in which employees do not commute to a central place of work, such as an office building, war ...

and secure off-site system access procedures. * Facilitating worker transfer by changing boots or authorizations instead of moving machines. * Using

thin client In computer networking, a thin client is a simple (low-performance) computer that has been optimized for establishing a remote connection with a server-based computing environment. They are sometimes known as ''network computers'', or in t ...

s for off-spec machines to eliminate the need for special boot images. Many organizations use thin clients for applications which require high security, involve unreliable users or repurpose older machines for continued use. A cascading strategy involves re-imaging older, off-spec machines to thin client boot images so that they may continue in use for some less demanding or more access-controlled applications.

References

{{Reflist

As virtual machine

Goals

References

See also