Live USB

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A live USB is a USB flash drive containing a full operating system which can be booted. Live USBs are closely related to Live CDs, and are sometimes used interchangeably. Like Live CDs, Live USBs can be used in embedded systems system administration, data recovery, or the testing of operating system distributions without committing to a permanent installation on the local hard disk drive. Many operating systems including Microsoft Windows XP embedded and many of the smaller Linux distributions can also be used from a USB flash drive.

1 Benefits and limitations
2 History
3 Types of Live USB
- 3.1 Live CD derived
- 3.2 Full install
4 Examples
5 See also
6 External links

Benefits and limitations

Live USBs share many of the benefits and limitations of Live CDs. One important advantage over Live CDs is the ability to conveniently change the data contained on the booting device. This allows for Live USBs to be used as personal storage, as it allows a user to carry their preferred operating system, applications, files and configuration with them, making it easy to share a single system between multiple users. Live USBs provide the additional benefit of enhanced privacy, because the user can easily carry the USB device with them or store it in a secure location (e.g. a safe) reducing the opportunities for others to access their data. The absence of moving parts in USB flash devices allows for faster seek time than is possible with hard drives or optical media, meaning small programs will start faster from a USB flash drive than from a local hard disk or Live CD. However, as USB devices typically achieve lower data transfer rates than internal hard drives, booting from a computer lacking USB 2.0 support can be very slow. Some computers, particularly older ones, may not have a BIOS that supports USB booting. In this case a computer can often be "redirected" to boot from a USB device through use of a bootable CD or floppy disk.

History

Proposed by IBM in 2004, in the papers "Reincarnating PCs with Portable SoulPads" (PDF & Summary) and Boot Linux from a FireWire device

Types of Live USB

Live CD derived

The first type of Live USB was created by simply taking the ISO image file from a Live-CD distribution and placing it on USB storage device and then making it bootable.

Advantages	Disadvantages
Simple to install. Compressed format allows for many applications in a small storage container. Updating whole image file is as easy as copying in a new one. Base installation can be as small as 50mb.	Difficult to update individual applications or install applications not part of the original image. Base install maximum size can be 700MB to 4GB for large installs. Many Live CDs are not set to write to their own filesystem as a CD is typically read only, thus it can sometimes be difficult to enable a Live USB OS to write to its flash drive. Encryption is only on a 'per-file' basis.

Full install

The second type of Live USB is closely related to a traditional operating system hard drive install with minor modifications like the elimination of swap partitions and files.

Advantages	Disadvantages
Updating applications or the whole thing is as easy as the parent distribution used to create it. Full system encryption possible. Easier to customise with the user's preferred Window Manager and applications. Base install usually starts at approximately 200MB (although some can be as little as 40MB) and grows as the user adds applications.	Initial installation is more complicated.

Examples

Full BSD installations

Installing FreeBSD onto a USB flash drive.
polyBSD - a NetBSD-derived live USB.
NetBSD livekey: non-destructive NetBSD/i386 on USB stick.

Linux live CD derivative

Damn Small Linux: Knoppix derived small installation, uses a 2.4 kernel.
Debian Live: Tool for building Debian Live CD, DVD, and USB images ( Current Images ).
Dyne:bolic: 100% free distribution for multimedia production, boots from CD and USB stick
Feather Linux: Another Knoppix derived installation, uses 2.4 kernel, roughly twice the size of Damn Small Linux.
Howto install Knoppix onto a USB flash thumb drive.
MCNLive: Mandriva derived Live CD, and Live-USB distribution.
NimbleX: Fast, easy to install and use and customize LinuxLive distribution.
PCLinuxOS
Pen Drive Linux: A project to support Linux on USB. Includes modified Live CD images for DSL, Knoppix, PCLinuxOS, Slax and Ubuntu on their Sourceforge download page,
Pentoo: Gentoo based Live CD and Live-USB distribution focused on penetration testing and security assessment.
Puppy Linux Designed for easy install on USB.
Slax: Slackware based installation.
SystemRescueCd: is a Linux system for repairing a system and recovering a data after a crash.
Ubuntu: Installing Ubuntu, Kubuntu Live Desktop, and/or Xubuntu Feisty Fawn
Virtual Privacy Machine: Debian derived Live-USB installation, includes Tor and other privacy tools.

Full Linux installations

Feraga.com: Automated Installer and Howtos for installing Debian GNU/Linux onto a USB flash thumbdrive with support for full system encryption (LUKS with UUID labels for partition identification). Base install is under 250MB without GUI applications.
Flash Linux: Installation based on Gentoo packages optimized for smaller USB flash media.
Gumstick Gentoo: Howto install Gentoo. Base install includes Fluxbox and runs about 750MB.
Knopperdisk: A small distribution based on Gentoo but designed to be run from USB pen drives or floppy disks.
Linux Mobile System: A distribution based on Fedora, repackaged to save space.
NimbleX: A small (200mb) distribution based on Slackware.
RUNT Linux: Based on Slackware with a 2.4 kernel and Umsdos filesystem. Designed as a network testing tool for students at North Carolina State University.

Macintosh

Also, with the Classic Mac OS, it is possible to copy the system folder onto a USB drive and have a Mac that supports booting off USB and booting into the Classic Mac OS boot off it.
You can install OS X on a USB and run it from there.

MS-DOS & Windows

MSDN: Booting from USB Devices [1]
Hiren's DOS BootCD on USB www.hiren.info/pages/bootcd-on-usb-disk with LOTS of utilities
Howto install the Windows Preinstallation Environment 2.0 onto a USB flash thumb drive.
Pe2USB: An application for formatting and making bootable, USB flash memory drives and USB hard disks and optionally copying the output from a successful BartPE/WinPE build to the device.