A live CD or live DVD (also called Live Disc) is a CD or DVD containing a bootable computer operating system. Live CDs are unique in that they have the ability to run a complete, modern operating system on a computer lacking mutable secondary storage, such as a hard disk drive. Live USB flash drives are similar to live CDs, but often have the added functionality of automatically and transparently writing changes back to their bootable medium.

The term “live” derives from the fact that these CDs each contain a complete, functioning and operational operating system on the distribution medium.

While a live CD typically does not alter the operating system or files already installed on a computer’s hard drive, many live CDs include mechanisms and utilities for altering the host computer’s hard drive, including permanent installation. This is important for the system management aspect of live CDs, such as removing viruses, drive imaging, and system recovery.

The default option, however, is to allow the user to return the computer to its previous state when the live CD is ejected and the computer is rebooted. It is able to run without permanent installation by placing the files that typically would be stored on a hard drive into RAM, typically in a RAM disk. However, this does cut down on the RAM available to applications, reducing performance somewhat. As of 2007, certain live CDs run a graphical user interface in as little as 32MB RAM.

While some live CDs are designed to “demo” or “test drive” a particular operating system (usually Linux or another free or open source operating system), there are live CDs made for many different uses.

Although some live CDs can load into memory in order to free the optical drive for other uses, loading the data off a CD-ROM is still slower than a typical hard drive boot, so this is rarely the default with large live CD images, but for smaller live CD images loading the filesystem directly into RAM can be highly practical. Loading the filesystem image into RAM can provide a significant performance boost as RAM is several orders of magnitude faster than a hard drive. Also, since RAM has no moving parts, a system running from a live CD loaded into RAM can run with improved power efficiency. Experienced users of the operating system may also use a live CD to determine whether and to what extent a particular operating system or version is compatible with a particular hardware configuration and certain peripherals, or as a way to know beforehand which computer or peripheral will work before buying. Users may also use a live CD to troubleshoot hardware, especially when a hard drive fails, and more generally as a recovery disc in case of problems. Some live CDs can save user-created files in a Windows partition, a USB drive, a network drive, or other accessible media.

A few additional uses include:

  • installing a Linux distribution to a hard drive
  • testing new versions of software
  • testing hardware
  • system repair and restoration
  • high security/non-invasive environment for a guest
  • cracking/stealing passwords
  • network security testing
  • being the primary or backup operating system for any computer
  • quick and simple clustering of computers [2]
  • computer forensics
  • playing video games
  • providing a secure server platform where crucial files cannot be permanently altered
  • providing a secure, reliable platform for the performance of high-vulnerability tasks such as internet banking;
  • Internet kiosks, which can be brought back to their original state by a reboot


Rescue and repair live CDs

BSD-based

Linux-based

Debian-based

Knoppix-based

A large number of live CDs are based on Knoppix. The list of those is in the derivatives section of the Knoppix article.

Ubuntu-based

These are based at least partially on Ubuntu, which is based on Debian:

Other

  • Damn Small Linux – very light and small with JWM and fluxbox, installable Live CD
  • Debian Live – Official live CD version of Debian.
  • DemoLinux (versions 2 and 3) – one of the very first Live CDs
  • Dreamlinux – installable Live CD to hard drives or flash media
  • Finnix – a small system administration Live CD. A PowerPC version is available.
  • Freeduc-cd – an educational live CD using Xfce realized with the help of UNESCO
  • gnuLinEx – includes GNOME
  • GNUstep – works on i386, AMD64, UltraSPARC, and PowerPC
  • grml – installable Live CD for sysadmins and text tool users
  • Kanotix – installable Live CD
  • Knoppix – the “original” Debian-based Live CD
  • MEPIS – installable Live CD
  • sidux[3] based on Debian unstable (Sid), installable Live CD, DVD
  • ULAnux/ULAnix – created in Mérida, Venezuela, and available on CD/DVD and USB forms

Gentoo-based

RPM-based

Mandriva-based

Slackware-based

  • SLAX – a Slackware derivative, modular and very easy to remaster
  • Simplelinux – simpleLinux is a live mini-distribution from slackware and uses the latest XFCE window-manager.
  • Taneu-Os – a Slackware 12.2 Live Cd in German Language

openSUSE-based

Red Hat Linux/Fedora-based

Other

  • PCLinuxOS – installable Live CD for desktop computing use
  • Granular – installable Live CD based on PCLinuxOS, featuring KDE and Enlightenment

Slackware-based

Other (Linux-based)

OpenSolaris-based

  • OpenSolaris – the official distribution supported by Sun Microsystems
  • MilaX small opensolaris based LiveCD and LiveUSB
  • Nexenta OS – combines the GNU userland with the OpenSolaris kernel.
  • BeleniX – full LiveCD and LiveUSB distribution
  • SchilliX – is the first OpenSolaris Live CD distribution.

GNU-based

Mac OS X-based

Microsoft Windows-based

  • BartPE (Windows XP/2003) – allows the creation of a bootable CD from Windows-install files
  • WinBuilder (Windows 2000/XP/2003/Vista) – allows the creation of a bootable CD from Windows-install files
  • Reatogo-X-PE – based on BartPE
  • VistaPE – a Live CD version for Windows Vista
  • UBCD4Win-a WinXP based Live CD with lots of recovery/system tools.
  • Microsoft Windows Preinstallation Environment

Microsoft representatives have described third-party efforts at producing Windows-based Live CDs as “improperly licensed” uses of Windows, unless you use it solely to rescue your own, properly licensed Installation. However, Nu2 Productions believes the use of BartPE is legal provided that one Windows license is purchased for each BartPE CD, and the Windows license is used for nothing else.[6]

The Microsoft sanctioned MS Windows Preinstallation Environment product is linked above, but only WinPE version 2.0 or newer is available freely for general use as part of the Windows Automated Installation Kit.[citation needed]

DOS-based

  • FreeDOS – the official “Full CD” 1.0 release includes a Live CD portion
  • FUZOMA – a Live CD educational software collection based on FreeDOS

Other operating systems

  • BeOS – all BeOS discs can be run in Live CD mode, although PowerPC versions need to be kickstarted from Mac OS 8
  • OS/2 Ecomstation Demo
  • Minix
  • AmigaOS 4 – installable Live CD which also can be used independently from any existing OS installations.
  • MorphOS – installable Live CD which can be also used as independent from any existing MorphOS installations.
  • AROS – offers Live CD for download on the project page
  • OpenVMS – installable Live CD
  • Plan 9 from Bell Labs – Plan 9 has a Live CD, which is also its install CD (and the installer is a shell script).
  • QNX
  • ReactOS
  • SkyOS
  • Syllable Desktop Live CD

See also

References

External links