Most flash drives ship preformatted with the
FAT or
FAT 32 file system. The ubiquity of this file system allows the drive to be accessed on virtually any host device with USB support. Also, standard FAT
maintenance utilities (e.g.
ScanDisk) can be used to repair or retrieve
corrupted data. However, because a flash drive appears as a USB-connected
hard drive to the host system, the drive can be
reformatted to any file system supported by the host operating system.
Defragmenting: Flash drives can be
defragmented, but this brings little advantage as there is no mechanical head that moves from fragment to fragment. Flash drives often have a large internal sector size, so defragmenting means accessing fewer sectors. Defragmenting shortens the life of the drive by making many unnecessary writes.
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Even Distribution: Some file systems are designed to distribute usage over an entire memory device without concentrating usage on any part (e.g. for a directory); this even distribution prolongs the life of simple flash memory devices. Some USB flash drives have this
functionality built into the software controller to prolong device life, while others do not, therefore the end user should check the specifications of his device prior to changing the file system for this reason.
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Hard Drive: Sectors are 512 bytes long, for compatibility with hard drives, and the first sector can contain a
Master Boot Record and a
partition table. Therefore USB flash units can be partitioned as hard drives.
[edit] Longevity
Barring physical destruction of the drive, the memory or USB connector of a flash drive will eventually fail.
SLC based memory is good for around 100,000 writes; more commonly used
MLC for around 10,000. The USB connector can withstand approximately 1,500 connect/disconnect cycles.
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[edit] Fake products
Fake USB flash drives are sometimes sold, claiming to have higher capacities than they actually have. These are typically low capacity USB drives which are modified so that they emulate larger capacity drives (e.g. a 2 GB drive being marketed as an 8 GB drive). When plugged into a computer, they report themselves as being the larger capacity they were sold as, but when data is written to them, either the write fails, the drive freezes up, or it overwrites existing data. Software tools exist to check and detect fake USB drives.
[21][22] In some cases it is possible to repair these devices to remove the false capacity information and use them normally.
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[edit] Personal data transport
The most common use of flash drives is to transport and store personal files such as documents, pictures and videos. Individuals also store medical alert information on MedicTag flash drives for use in emergencies and for disaster preparation.
[edit] Secure storage of data, application and software files
With wide deployment(s) of flash drives being used in various environments (secured or otherwise), the issue of data and information security remains of the utmost importance. The use of
biometrics and
encryption is becoming the norm with the need for increased security for data;
OTFE systems are particularly useful in this regard, as they can transparently encrypt large amounts of data. In some cases a
Secure USB Drive may use a hardware-based encryption mechanism that uses a hardware module instead of software for strongly encrypting data.
IEEE 1667 is an attempt to create a generic authentication platform for USB drives and enjoys the support of
Microsoft with support in
Windows 7 and in Windows Vista Service Pack 2 with a hotfix.
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[edit] System administration
Flash drives are particularly popular among system and network administrators, who load them with configuration information and software used for system maintenance, troubleshooting, and recovery. They are also used as a means to transfer recovery and antivirus software to infected PCs, allowing a portion of the host machine's data to be archived. As the drives have increased in storage space, they have also replaced the need to carry a number of CD ROMs and installers which were needed when reinstalling or updating a system.
[edit] Application carriers
Flash drives are used to carry
applications that run on the host computer
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