Editing USB flash drive (section)

====Failures====
Like all flash memory devices, flash drives can sustain only a limited number of write and erase cycles before the drive fails.<ref>[http://www.bress.net/blog/archives/114-How-Long-Does-a-Flash-Drive-Last.html How Long Does a Flash Drive Last? – Josh's Blog] {{Webarchive|url=https://web.archive.org/web/20100213060937/http://www.bress.net/blog/archives/114-How-Long-Does-a-Flash-Drive-Last.html |date=2010-02-13 }}. 2008-05-23, Bress.net. Retrieved on 2011-05-18.</ref>{{Unreliable source?|date=December 2011}}<ref>{{Cite web|url=http://www.corsairmemory.com/_faq/FAQ_flash_drive_wear_leveling.pdf|archive-url=https://web.archive.org/web/20090206095926/http://www.corsairmemory.com/_faq/FAQ_flash_drive_wear_leveling.pdf|url-status=dead|title=What is flash drive wear leveling<!-- Bot generated title -->|archive-date=February 6, 2009}}</ref> This should be a consideration when using a flash drive to run application software or an operating system. To address this, as well as space limitations, some developers have produced special versions of operating systems (such as [[Linux]] in [[Live USB]])<ref>[http://linux-usb.sourceforge.net/USB-guide/x498.html Mass Storage Devices] {{Webarchive|url=https://web.archive.org/web/20100304071224/http://linux-usb.sourceforge.net/USB-guide/x498.html |date=2010-03-04 }}. Linux-usb.sourceforge.net. Retrieved on 2011-05-18.</ref> or commonplace applications (such as [[Mozilla Firefox]]) designed to run from flash drives. These are typically optimized for size and configured to place temporary or intermediate files in the computer's main RAM rather than store them temporarily on the flash drive.

When used in the same manner as external rotating drives (hard drives, optical drives, or floppy drives), i.e. in ignorance of their technology, USB drives' [[failure of electronic components|failure]] is more likely to be sudden: while rotating drives ''can'' fail instantaneously, they more frequently give some indication (noises, slowness) that they are about to fail, often with enough advance warning that data can be removed before total failure. USB drives give little or no advance warning of failure. Furthermore, when internal wear-leveling is applied to prolong life of the flash drive, once failure of even part of the memory occurs it can be difficult or impossible to use the remainder of the drive, which differs from magnetic media, where bad sectors can be marked permanently not to be used.<ref>{{cite web |last=Notenboom |first=Leo A. |url=http://ask-leo.com/how_do_i_fix_bad_sectors_on_a_flash_drive.html |title=How do I fix bad sectors on a flash drive? |website=Ask-leo.com |date=2008-05-06 |access-date=2017-06-06 |archive-date=2017-06-13 |archive-url=https://web.archive.org/web/20170613234348/http://ask-leo.com/how_do_i_fix_bad_sectors_on_a_flash_drive.html |url-status=live }}</ref>

Most USB flash drives do not include a [[write protection]] mechanism. This feature, which gradually became less common, consists of a switch on the housing of the drive itself, that prevents the host computer from writing or modifying data on the drive. For example, write protection makes a device suitable for repairing [[computer virus|virus]]-contaminated host computers without the risk of infecting a USB flash drive itself. In contrast to [[SD card]]s, write protection on USB flash drives (when available) is connected to the drive circuitry, and is handled by the drive itself instead of the host (on SD cards handling of the write-protection notch is optional).

A drawback to the small physical size of flash drives is that they are easily misplaced or otherwise lost. This is a particular problem if they contain sensitive data (see [[data security]]). As a consequence, some manufacturers have added encryption hardware to their drives, although [[Comparison of disk encryption software|software encryption systems]] which can be used in conjunction with any [[mass storage]] medium will achieve the same result. Most drives can be attached to keychains or lanyards. The USB plug is usually retractable or fitted with a removable protective cap.