Live USB
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A live USB is a portable
system administration, data recovery
, or test driving, and can persistently save settings and install software packages on the USB device.
Many operating systems including Windows XP Embedded and a large portion of Linux and BSD distributions can run from a USB flash drive, and Windows 8 Enterprise has a feature titled Windows To Go for a similar purpose.
Background
To repair a computer with booting issues, technicians often use lightweight operating systems on
bootable media and a command-line interface
. The development of the first live CDs with graphical user interface made it feasible for non-technicians to repair malfunctioning computers. Most Live CDs are Linux-based, and in addition to repairing computers, these would occasionally be used in their own right as operating systems.
macOS from USB.[2] Specialized USB-based booting was proposed by IBM in 2004 with Reincarnating PCs with Portable SoulPads and Boot Linux from a FireWire device.[3][4]
Benefits and limitations
Live USBs share many of the benefits and limitations of live CDs, and also incorporate their own.
Benefits
- In contrast to live CDs, the data contained on the booting devicecan 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 safe), reducing the opportunities for others to access their data. On the other hand, a USB device is easily lost or stolen, so data encryption and backup is even more important than with a typical desktop system.
- The absence of moving parts in USB flash devices allows true USB 2.0or newer can be very slow.
Limitations
- LiveUSB OSes like casper filesystem overlay (casper-rw) that, once full or out of flash drive space, becomes unusable and the OS ceases to boot.[citation needed]
- USB controllers on add-in cards (e.g. ISA, PCI, and PCI-E) are almost never capable of being booted from, so systems that do not have native USB controllers in their chipset (e.g. such as older ones before USB) likely will be unable to boot from USB even when USB is enabled via such an add-in card.
- Some computers, particularly older ones, may not have a BIOS 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 disk.[5][6][7]
- Some Extensible Firmware Interface (EFI) firmware can recognize and boot from USB drives, it can do this only in EFI mode. When the firmware switches to "legacy" BIOS mode, it no longer recognizes USB drives. Non-Macintosh systems, notably Windows and Linux, may not be typically booted in EFI mode and thus USB booting may be limited to supported hardware and software combinations that can easily be booted via EFI.[8]However, programs like Mac Linux USB Loader can alleviate the difficulties of the task of booting a Linux-live USB on a Mac. 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 WORM 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;.
Setup
Fedora Live USB Creator, and UNetbootin. There are also software applications available that can be used to create a Multiboot live USB; some examples include YUMI Multiboot Bootable USB Creator[10] and Ventoy. A few Linux distributions and live CDs have ready-made scripts which perform the steps below automatically. In addition, on Knoppix and Ubuntu extra applications can be installed, and a persistent file system can be used to store changes. A base install ranges between as little as 16 MiB (Tiny Core Linux
) to a large DVD-sized install (4 gigabytes).
To set up a live USB system for commodity PC hardware, the following steps must be taken:
- A USB flash drive 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 MBR 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 systemscan be used too)
- A bootloader must be installed to the partition (most often using syslinuxwhen 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
- USB support in the BIOS’s boot menu (although there are ways to get around this; actual use of a CD or DVD can allow the user to choose if the medium can later be written to. Write Once Read Manydiscs allow certainty that the live system will be clean the next time it is rebooted.)
live USB tools
are simple to use.
Full installation
One alternative to the live operating-system solution would be a full installation; that is, a traditional installation, but without swap partitions. This option has the advantage of being efficient for the software, as it eliminates the need for the device to retain – separate from the persistent file – the operating-system’s installer software. However, full installation is not without disadvantages; due to the additional write cycles that it requires, the life of the flash drive may be slightly reduced. To mitigate this, some live systems are designed to store changes in RAM until the user initiates a system powerdown, which triggers the actual writes to the device. The trade-off is greater risk of lost work, in the case of an abnormal abort. Beyond these, another factor to consider is that, if the transfer speed of the storage device is poor, then performance can be reduced to a rate more typical of legacy computers – even for machines with modern components. This issue can usually be overcome by installing to a USB hard drive, as they generally perform better than flash drives, regardless of the connector.
Microsoft Windows
Although many live USBs rely on booting an open-source operating system such as Linux, it is possible to create live USBs for Microsoft Windows by using
WinToUSB.[12]
See also
- Boot disk
- List of live CDs
- List of tools to create Live USB systems
- List of Linux distributions that run from RAM
- Live USB creator
- Comparison of Linux Live CDs
- Self-booting diskette
- UNetbootin
References
- ^ "USB Info and Benefits of Dual-Channel USB". Apple (published February 20, 2012). September 16, 2003. Archived from the original on May 12, 2013. Retrieved September 25, 2016.
Bootable USB drives: A storage device such as a SuperDisk, Zip disk, or other USB storage drive can be used to hold a valid system folder and used at startup.
- ^ "Starting from an external USB storage device (Intel-based Macs)". Apple. March 22, 2016. Archived from the original on May 22, 2016. Retrieved September 25, 2016.
- ^ Singer, Michael (August 15, 2005). "IBM brains capture a PC's soul". CNET. CBS Interactive. Archived from the original on September 27, 2016. Retrieved September 25, 2016.
- IBM DeveloperWorks. IBM. Archived from the originalon January 17, 2007. Retrieved May 15, 2016.
- ^ Trevor (May 6, 2010). "Boot from a USB Drive Even If Your BIOS Won't Let You". How-To Geek. Archived from the original on September 23, 2016. Retrieved September 25, 2016.
- ^ "Plop Boot Manager". February 7, 2012. Archived from the original on February 8, 2012. Retrieved September 25, 2016.
- ^ "Universal USB Installer - Bootable USB Software - UUI". PenDrive Linux. 2010-02-10. Retrieved February 17, 2024.
- ^ knome (December 14, 2013). "MactelSupportTeam/EFI-Boot-Mactel". Ubuntu Community Help Wiki. Canonical Ltd. Archived from the original on March 4, 2016. Retrieved September 25, 2016.
- ^ "XFCE minimum install HD". Linux Mint Forums. Archived from the original on September 27, 2016. Retrieved September 25, 2016.
Live cd only write to the swap partition if your pc has one.
If it doesn't it'll only use your RAM. - ^ "YUMI - Multiboot USB Creator | Easily Boot from USB Windows". Pendrive Linux. 13 March 2011. Archived from the original on 2017-10-23. Retrieved 2024-02-17.
- ^ nnamuhcs. "Create a Bootable USB Flash Drive". docs.microsoft.com. Archived from the original on 2018-09-16. Retrieved 2021-09-15.
- ^ Gordon, Whitson (21 April 2014). "How to Run a Portable Version of Windows from a USB Drive". Lifehacker. Gawker Media. Archived from the original on September 25, 2016. Retrieved September 25, 2016.
External links
Wikimedia Commons has media related to Live USB.
Wikibooks has a book on the topic of: Live distro and Full Linux Install
- The Differences Between Persistent Live USB and Full Linux Install on USB
- Universal USB Installer
- Partitionless Installation
- Tutorial – How to Set your BIOS to boot from CD or USB
- HOW TO: Create a working Live USB
- Debian Live project
- How to create a Live USB in Ubuntu
- Casper
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