- This is simple for the end-user, and more likely to be done;
- The drive is small and convenient, and more likely to be carried off-site for safety;
- The drives are less fragile mechanically and magnetically than tapes;
- The capacity is often large enough for several backup images of critical data;
- And flash drives are cheaper than many other backup systems.
[edit] Advantages and disadvantages
[edit] Advantages
Data stored on flash drives is impervious to scratches and dust, and flash drives are mechanically very robust making them suitable for transporting data from place to place and keeping it readily at hand. Most personal computers support USB as of 2010[update].Flash drives also store data densely compared to many removable media. In mid-2009, 256 GB drives became available, with the ability to hold many times more data than a DVD or even a Blu-ray disc.
Compared to hard drives, flash drives use little power, have no fragile moving parts, and for most capacities are small and light.
Flash drives implement the USB mass storage device class so that most modern operating systems can read and write to them without installing device drivers. The flash drives present a simple block-structured logical unit to the host operating system, hiding the individual complex implementation details of the various underlying flash memory devices. The operating system can use any file system or block addressing scheme. Some computers can boot up from flash drives.
Specially manufactured flash drives are available that have a tough rubber or metal casing designed to be waterproof and virtually "unbreakable". These flash drives retain their memory even after being submerged in water,[33] even through a machine wash. Leaving such a flash drive out to dry completely before allowing current to run through it has been known to result in a working drive with no future problems. Channel Five's Gadget Show cooked one of these flash drives with propane, froze it with dry ice, submerged it in various acidic liquids, ran over it with a jeep and fired it against a wall with a mortar. A company specializing in recovering lost data from computer drives managed to recover all the data on the drive.[34] All data on the other removable storage devices tested, using optical or magnetic technologies, were destroyed.
[edit] Disadvantages
Like all flash memory devices, flash drives can sustain only a limited number of write and erase cycles before the drive fails.[35][36] 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)[37] 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.Most USB flash drives do not include a write-protect mechanism, although some have a switch on the housing of the drive itself to keep the host computer from writing or modifying data on the drive. Write-protection makes a device suitable for repairing virus-contaminated host computers without risk of infecting the USB flash drive itself.
A drawback to the small size is that they are easily misplaced, left behind, or otherwise lost. This is a particular problem if the data they contain are sensitive (see data security). As a consequence, some manufacturers have added encryption hardware to their drives—although software encryption systems which can be used in conjunction with any mass storage medium achieve the same thing,[citation needed]. Most drives can be attached to keychains, necklaces and lanyards. The USB plug is usually fitted with a removable and easily lost protective cap, or is retractable.
USB flash drives are more expensive per unit of storage than large hard drives, but are less expensive in capacities of a few tens of gigabytes as of 2011[update][38][39]. Maximum available capacity is increasing with time, but is less than larger hard drives. This balance is changing, but the rate of change is slowing.
[edit] Comparison with other portable storage
[edit] Tape
The applications of current data tape cartridges hardly overlap those of flash drives: on tape, cost per gigabyte is very low for large volumes, but the individual drives and media are expensive. Media has a very high capacity and very fast transfer speeds, but store data sequentially and is very slow for random seek of data. While disk-based backup is now the primary medium of choice for most companies, tape backup is still popular for taking data off-site for worst-case scenarios and for very large volumes (more than a few hundreds of TB). See LTO tapes.[edit] Floppy disk
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