Live USB

From Wikipedia, the free encyclopedia

a Live USB of Ubuntu, running Firefox, OpenOffice.org and nautilus

A Live USB or LiveUSB or USB Live Distro 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 References

[edit] Benefits and limitations

Live USBs share many of the benefits and limitations of Live CDs.

Live USB distros can be run from the portable flash device in the same fashion (but much faster) than it would from the Live CD.

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.

[edit] History

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

[edit] Types of Live USB

[edit] 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.

[edit] 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.	Only easy to install if the operating system provides support. Due to the additional read/write cycles that occur on a full blown install, the life of your flash drive may be slightly reduced.

[edit] Examples

BackTrack
BeleniX: Customized OpenSolaris installs including Live-CD and Live-USB.^[1]
Damn Small Linux: Knoppix derived small installation, uses a 2.4 kernel, with JWM as default user interface.
Debian ^[2] ^[3]
Dyne:bolic: 100% free distribution for multimedia production, boots from CD and USB stick, with Xfce as default user interface.
Fedora ^[4]
Gentoo ^[5] Gentoo USB Live.
Knopperdisk: A small distribution based on Gentoo but designed to be run from USB pen drives or floppy disks.
MCNLive: Mandriva derived Live CD, and Live-USB distribution.
Minix ^[6]
NimbleX: A small (200mb) distribution based on Slackware.
OpenSolaris: The Distribution Constructor project has tools allowing users to build an install image.^[7]
PCLinuxOS
OSx86 ^[8]
Pentoo: Gentoo based Live CD and Live-USB distribution focused on penetration testing and security assessment.
Puppy Linux Designed for easy install on USB.
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.
Slax: Slackware based installation.
Ubuntu (can be installed directly to a flash drive or USB external drive using the Live USB system creator)
Windows Preinstallation Environment: Freely available version of a live Windows installation, command line only.