Live USB
Encyclopedia
USB flash drive
A flash drive is a data storage device that consists of flash memory with an integrated Universal Serial Bus interface. flash drives are typically removable and rewritable, and physically much smaller than a floppy disk. Most weigh less than 30 g...
or a USB external hard disk drive containing a full operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
that can be booted
Booting
In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...
. Live USBs are closely related to live CD
Live CD
A live CD, live DVD, or 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...
s, but sometimes have the ability to persistently save settings and permanently install software packages back onto the USB device. Like live CDs, live USBs can be used in embedded systems for system administration, data recovery
Data recovery
Data recovery is the process of salvaging data from damaged, failed, corrupted, or inaccessible secondary storage media when it cannot be accessed normally. Often the data are being salvaged from storage media such as internal or external hard disk drives, solid-state drives , USB flash drive,...
, or the testing of operating system distributions without committing to a permanent installation on the local hard disk drive. Many operating systems including Mac OS 9, Mac OS X, Microsoft Windows XP Embedded and many of the Linux distribution
Linux distribution
A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications...
s and BSD
Berkeley Software Distribution
Berkeley Software Distribution is a Unix operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995...
distributions can also be used from a USB flash drive. Windows 8
Windows 8
Windows 8 is the codename for the next version of the Microsoft Windows computer operating system following Windows 7. It has many changes from previous versions. In particular it adds support for ARM microprocessors in addition to the previously supported x86 microprocessors from Intel and AMD...
is also planned to be able to run from a USB drive, with Windows To Go
Windows To Go
Windows To Go is a feature in Windows 8 that allows the entire system to run from USB mass storage devices such as flash drives and external hard drives....
.
History
Since 1999, Apple Macintosh computers (beginning with the Power Mac G4Power Mac G4
The Power Mac G4 was a series of personal computers that was designed, manufactured, and sold by Apple between 1999 and 2004. They used the PowerPC G4 series of microprocessors. They were heralded by Apple to be the first personal supercomputers, reaching speeds of 4 to 20 Gigaflops...
with AGP graphics and the slot-loading iMac G3
IMac G3
The iMac G3 was the first model of the iMac line of personal computers made by Apple Inc. , and the originator of the Legacy-free PC market category. Like the first Macs, the iMac G3 is an all-in-one personal computer, encompassing both the monitor and the system unit in a single enclosure...
models) have been able to boot from USB. Intel-based Macs support booting Mac OS X from USB.
Specialized USB-based booting was proposed by IBM in 2004, in the papers "Reincarnating PCs with Portable SoulPads" (PDF & Summary) and Boot Linux from a FireWire device.
Benefits and limitations
Live CD
A live CD, live DVD, or 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...
s.
Benefits
- In contrast to live CDs, the data contained on the booting device can be changed and additional data stored on the same device. A user can carry their preferred operating system, applications, configuration, and personal files with them, making it easy to share a single system between multiple users.
- Live USBs provide the additional benefit of enhanced privacy because users can easily carry the USB device with them or store it in a secure location (e.g. a safeSafeA safe is a secure lockable box used for securing valuable objects against theft or damage. A safe is usually a hollow cuboid or cylinder, with one face removable or hinged to form a door. The body and door may be cast from metal or formed out of plastic through blow molding...
), reducing the opportunities for others to access their data. On the other hand, a USB device is easily lost or stolen, so data encryptionEncryptionIn cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...
and backupBackupIn information technology, a backup or the process of backing up is making copies of data which may be used to restore the original after a data loss event. The verb form is back up in two words, whereas the noun is backup....
is even more important than with a typical desktop system.
- The absence of moving parts in USB flash devices allows true random accessRandom accessIn computer science, random access is the ability to access an element at an arbitrary position in a sequence in equal time, independent of sequence size. The position is arbitrary in the sense that it is unpredictable, thus the use of the term "random" in "random access"...
avoiding the rotational latency and seek time (see mechanical latency) of 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.
Limitations
- Some computers, particularly older ones, may not have a BIOSBIOSIn IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....
that supports USB booting. Many which do support USB booting may still be unable to boot the device in question. In these cases a computer can often be "redirected" to boot from a USB device through use of an initial bootable CD or floppy diskFloppy diskA floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...
.
- Intel-based Macintosh computers have limitations when booting from USB devices – while the Extensible Firmware InterfaceExtensible Firmware InterfaceThe Unified Extensible Firmware Interface is a specification that defines a software interface between an operating system and platform firmware...
(EFI) firmwareFirmwareIn electronic systems and computing, firmware is a term often used to denote the fixed, usually rather small, programs and/or data structures that internally control various electronic devices...
can recognize and boot from USB drives, it can only do this in EFI mode. When the firmware switches to "legacy" BIOS mode, it no longer recognizes USB drives. Non OSX systems may not be typically booted in EFI mode, notably Windows and Linux, and thus USB booting may be limited to supported hardware and software combinations, which can easily be booted via EFI. This limitation could be fixed by either changing the Apple firmware to include a USB driver in BIOS mode, or changing the operating systems to remove the dependency on the BIOS.
- Due to the additional write cycles that occur on a full-blown installation, the life of the flash drive may be slightly reduced. This doesn't apply to systems particularly designed for live systems which keep all changes in RAMRam-Animals:*Ram, an uncastrated male sheep*Ram cichlid, a species of freshwater fish endemic to Colombia and Venezuela-Military:*Battering ram*Ramming, a military tactic in which one vehicle runs into another...
until the user logs off. A write-locked SD card (known as a Live SD the solid-state counterpart to a Live CDLive CDA live CD, live DVD, or 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...
) in a USB flash card reader adapter is an effective way to avoid any duty cycles on the flash medium from writes and circumvent this problem. The SD card as a WORMWrite Once Read ManyA Write Once Read Many or WORM drive is a data storage device where information, once written, cannot be modified. On ordinary data storage devices, the number of times data can be modified is not limited, except by the rated lifespan of the device, as modification involves physical changes that...
device has an essentially unlimited life. An OS such as Linux can then run from the live USB/SD card and use conventional media for writing, such as magnetic disks, to preserve system changes (see Persistence (computer science)Persistence (computer science)Persistence in computer science refers to the characteristic of state that outlives the process that created it. Without this capability, state would only exist in RAM, and would be lost when this RAM loses power, such as a computer shutdown....
).
Principle of installation
Various applications exist to create live USBs; examples include the Fedora Live USB CreatorFedora Live USB creator
The Fedora Live USB creator is an official tool designed to create Live USBs of Fedora.-Features:*Cross-platform *Non-destructive install...
and UNetbootin
UNetbootin
UNetbootin is a cross-platform utility that can create live USB systems and can load a variety of system utilities or install various Linux distributions and other operating systems without a CD.- USB Install :...
and MultiSystem LiveUSB MultiBoot, which works with a variety of distributions. A few Linux distribution
Linux distribution
A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications...
and live CDs have ready-made scripts which perform the steps below automatically. In addition on some (Knoppix, Ubuntu), extra applications can be installed, and a persistent
Persistence (computer science)
Persistence in computer science refers to the characteristic of state that outlives the process that created it. Without this capability, state would only exist in RAM, and would be lost when this RAM loses power, such as a computer shutdown....
file system
File system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
can be used to store changes.
To set up a live USB system for commodity PC hardware, the following steps need to be done:
- A USB flash driveUSB flash driveA flash drive is a data storage device that consists of flash memory with an integrated Universal Serial Bus interface. flash drives are typically removable and rewritable, and physically much smaller than a floppy disk. Most weigh less than 30 g...
needs to be connected to the system, and be detected by it - One or more partitions may need to be created on the USB flash drive
- The "bootable" flag must be set on the primary partition on the USB flash drive
- An MBRMaster boot recordA master boot record is a type of boot sector popularized by the IBM Personal Computer. It consists of a sequence of 512 bytes located at the first sector of a data storage device such as a hard disk...
must be written to the primary partition of the USB flash drive - The partition must be formatted (most often in FAT32 format, but other file systemFile systemA file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
s can be used too) - A bootloader must be installed to the partition (most often using syslinuxSYSLINUXThe SYSLINUX Project is a suite of lightweight IBM PC MBR bootloaders for starting up computers with the Linux kernel. It is the work of H. Peter Anvin, and consists of several separate systems, the best-known of which is ISOLINUX.-List:...
when installing a Linux system) - A bootloader configuration file (if used) must be written
- The necessary files of the operating system and default applications must be copied to the USB flash drive
- Language and keyboard files (if used) must be written to the USB flash drive
(Actual use of a CD or DVD will allow the user to choose if the medium can later be written to. Write Once Read Many
Write Once Read Many
A Write Once Read Many or WORM drive is a data storage device where information, once written, cannot be modified. On ordinary data storage devices, the number of times data can be modified is not limited, except by the rated lifespan of the device, as modification involves physical changes that...
discs allow certainty that the live system will be clean the next time it is re-booted.)
Knoppix
Knoppix
Knoppix, or KNOPPIX , is an operating system based on Debian designed to be run directly from a CD / DVD or a USB key , one of the first of its kind for any operating system. Knoppix was developed by Linux consultant Klaus Knopper. When starting a program, it is loaded from the removable medium...
live CDs have a utility that, on boot, allows users to declare their intent to write the operating system's file structures either temporarily, to a RAM disk
RAM disk
A RAM disk or RAM drive is a block of RAM that a computer's software is treating as if the memory were a disk drive...
, or permanently, on disk and flash media to preserve any added configurations and security updates. This can be easier than re-creating the USB system but may be moot since many current (circa 2010) live USB tools are simple to use.
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 |
|---|---|
|
Examples
- BeleniXBeleniXBeleniX is an operating system distribution built using the OpenSolaris source base. It can be used as a Live CD as well as installed to hard disk. From the information provided on the BeleniX website, it may appear that currently, BeleniX is compiled only for 32-bit execution...
: Customized OpenSolarisOpenSolarisOpenSolaris was an open source computer operating system based on Solaris created by Sun Microsystems. It was also the name of the project initiated by Sun to build a developer and user community around the software...
installs including live CD and live USB. - FedoraFedora (operating system)Fedora is a RPM-based, general purpose collection of software, including an operating system based on the Linux kernel, developed by the community-supported Fedora Project and sponsored by Red Hat...
(with Fedora Live USB creatorFedora Live USB creatorThe Fedora Live USB creator is an official tool designed to create Live USBs of Fedora.-Features:*Cross-platform *Non-destructive install...
) - GentooGentoo LinuxGentoo Linux is a computer operating system built on top of the Linux kernel and based on the Portage package management system. It is distributed as free and open source software. Unlike a conventional software distribution, the user compiles the source code locally according to their chosen...
Gentoo USB Live. - HaikuHaiku (operating system)Haiku is a free and open source operating system compatible with BeOS. Its development began in 2001, and the operating system became self-hosting in 2008, with the first alpha release in September 2009, the second in May 2010 and the third in June 2011....
: the Installer tool installs the operating systemOperating systemAn operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
onto a hard disk or a USB Live indifferently. - KnoppixKnoppixKnoppix, or KNOPPIX , is an operating system based on Debian designed to be run directly from a CD / DVD or a USB key , one of the first of its kind for any operating system. Knoppix was developed by Linux consultant Klaus Knopper. When starting a program, it is loaded from the removable medium...
, one of the first live Linux distributions - OpenBSDOpenBSDOpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995...
- OpenSolarisOpenSolarisOpenSolaris was an open source computer operating system based on Solaris created by Sun Microsystems. It was also the name of the project initiated by Sun to build a developer and user community around the software...
: The Distribution Constructor project has tools allowing users to build an install image. - OS-9 RTOSOS-9OS-9 is a family of real-time, process-based, multitasking, multi-user, Unix-like operating systems, developed in the 1980s, originally by Microware Systems Corporation for the Motorola 6809 microprocessor. It is currently owned by RadiSys Corporation....
: The standard OS-9 Configuration Wizard for X86 creates bootable USB sticks. OS-9 5.0 for X86 will support the creation of bootable CDs. - OSx86OSx86OSx86 is a collaborative hacking project to run the Mac OS X computer operating system on non-Apple personal computers with x86 architecture and x86-64 compatible processors...
: some "hacked" Mac OS X images can be written to a USB flash drive and turn it into a bootable Mac OS X system. - Puredyne: live CD/DVD/USB distribution for media artists and designers.
- PCLinuxOSPCLinuxOSPCLinuxOS, often shortened to PCLOS, is a GNU/Linux distribution, with KDE Plasma Desktop as its default user interface. It is a primarily free software operating system for personal computers aimed at ease of use...
: Version 2009.1 comes with a live USB creator tool, version 2008 "MiniMe" can be installed manually. - Puppy LinuxPuppy LinuxPuppy Linux is a lightweight Linux distribution that focuses on ease of use. The entire system can be run from RAM, allowing the boot medium to be removed after the operating system has started...
Designed for easy install on USB. - Sugar: Sugar on a Stick is a LiveUSB for children and learning.
- Super OS: usb-creator and cd2usb already included on the DVD.
- UbuntuUbuntu (operating system)Ubuntu is a computer operating system based on the Debian Linux distribution and distributed as free and open source software. It is named after the Southern African philosophy of Ubuntu...
(can be installed directly to a flash drive or USB external hard drive manually by using tools like usb-creator, UNetbootinUNetbootinUNetbootin is a cross-platform utility that can create live USB systems and can load a variety of system utilities or install various Linux distributions and other operating systems without a CD.- USB Install :...
or cd2usb) - Windows To GoWindows To GoWindows To Go is a feature in Windows 8 that allows the entire system to run from USB mass storage devices such as flash drives and external hard drives....
: Windows 8Windows 8Windows 8 is the codename for the next version of the Microsoft Windows computer operating system following Windows 7. It has many changes from previous versions. In particular it adds support for ARM microprocessors in addition to the previously supported x86 microprocessors from Intel and AMD...
feature that will allow the entire system to run from a USB drive, including programs, settings and documents - Windows Preinstallation EnvironmentWindows Preinstallation EnvironmentWindows Preinstallation Environment is a lightweight version of Windows XP, Windows Server 2003, Windows Vista, Windows 7, or Windows Server 2008 R2 that is used for the deployment of workstations and servers...
: Freely available version of a live WindowsMicrosoft WindowsMicrosoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
installation, command-line only.
Comparison
| Distribution | Alternatives to live Cd creation | File saving | Application saving | Boot methods |
|---|---|---|---|---|
| Fedora Fedora (operating system) Fedora is a RPM-based, general purpose collection of software, including an operating system based on the Linux kernel, developed by the community-supported Fedora Project and sponsored by Red Hat... 9 |
Netinstaller (downloads iso & makes Usb), UNetbootin | in folder | none | |
| Gobolinux GoboLinux GoboLinux is a free and open source operating system whose most prominent feature is a reorganization of the traditional Linux file system. Rather than following the Filesystem Hierarchy Standard like most Unix-like systems, each program in a GoboLinux system has its own subdirectory tree, where... |
Zip + sh&bat scripts | N/A | N/A | 2ram (gobolinux toram) |
| sidux Sidux aptosid is a desktop-oriented operating system based on the "unstable" branch of Debian, which uses the codename Sid. It was known as sidux until September 2010. The distribution consists of a Live CD for the x86 architecture installable to a hard drive through a graphical installer... |
USB installer GUI | in folder, on USB stick | auto | normal |
| Slax SLAX Slax is a LiveCD Linux distribution based on Slackware and is currently being developed by Tomáš Matějíček. Packages can be selected in a website where users can build a custom Slax iso image. Slax slogan refers to the software as a "Pocket Operating System"... |
Zip + sh&bat scripts, UNetbootin | N/A | N/A | |
| SliTaz SliTaz GNU/Linux SliTaz GNU/Linux is a community-based software project started in 2006 by Christophe Lincoln. It is a Linux distribution with a root filesystem that takes up approximately 100 MB of disk space, and its ISO image installation media is around 30 MB... |
none & from internal drive($tazusb) | in hacker folder | through script (Tazusb) | 2ram - lowram |
| (K,X)Ubuntu Ubuntu (operating system) Ubuntu is a computer operating system based on the Debian Linux distribution and distributed as free and open source software. It is named after the Southern African philosophy of Ubuntu... |
UNetbootin UNetbootin UNetbootin is a cross-platform utility that can create live USB systems and can load a variety of system utilities or install various Linux distributions and other operating systems without a CD.- USB Install :... |
auto | auto | |
| Wolvix Wolvix Wolvix is a desktop-oriented Linux distribution based on Slackware, mainly targeted at home users, and strives to provide a balance between everyday computing tasks, creativity, work and enjoyment... |
none (Control Panel) | auto after making permanent space (Control panel) | auto | AllUsb - 2Ram |
Syslinux
SYSLINUX
The SYSLINUX Project is a suite of lightweight IBM PC MBR bootloaders for starting up computers with the Linux kernel. It is the work of H. Peter Anvin, and consists of several separate systems, the best-known of which is ISOLINUX.-List:...
is a program that makes a USB storage device bootable (they are often used after extracting files to the formatted media).
See also
- Extensible Firmware InterfaceExtensible Firmware InterfaceThe Unified Extensible Firmware Interface is a specification that defines a software interface between an operating system and platform firmware...
- extlinux
- Live CDLive CDA live CD, live DVD, or 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...
- Comparison of Linux Live CDs
- Disk cloningDisk cloningDisk cloning is the process of copying the contents of one computer hard disk to another disk or to an "image" file. Often, the contents of the first disk are written to an image file as an intermediate step, and the second disk is loaded with the contents of the image...
- List of live CDs
- Persistence (computer science)Persistence (computer science)Persistence in computer science refers to the characteristic of state that outlives the process that created it. Without this capability, state would only exist in RAM, and would be lost when this RAM loses power, such as a computer shutdown....
- List of tools to create Live USB systems
- Boot diskBoot diskA boot disk is a removable digital data storage medium from which a computer can load and run an operating system or utility program. The computer must have a built-in program which will load and execute a program from a boot disk meeting certain standards.Boot disks are used for:* Operating...
- Portable Apps