Next to accidental deletion, the most common way to lose
data from any kind of portable memory device is to lose the device itself.
The best data recovery tools in the world won't help if the flash drive has
dropped from one's pocket onto the sidewalk. Data recovery is
out of the question here, but there
are steps you can take to ensure that valuable data is useless to whoever
eventually finds the your former possession. Many USB drives will come pre-installed with data encryption
programs, so that partitions can be set up on the device for secure and
non-secure file storage. Major companies like Kingston, Crucial and SanDisk usually offer such extra's at no
charge with their products, small manufacturers selling USB memory may not.
Almost all flash memory devices use some form of 'hot pluggable' interface to
connect them with the various electronic devices they support. Hot
pluggable means that the memory can be attached and removed from a powered-on
device without fear of damage or hardware failure. USB is the most obvious
example of this technology, and one that we are all familiar with. The one
problem with this type of interface is the sense of invulnerability it engenders
in the user. We become so accustomed to inserting and removing our flash
memory devices at will that we often forget to make sure that all data transfer
tasks have stopped first.
There is no surer way to mess up a portable storage device than to yank it
out of its socket when it is halfway through an operation...
Unlike most other forms of media, flash memory devices are commonly used in a
variety of devices. Digital cameras, media players, DA players, DVD
players and an assortment of other electronic devices all can use these
flexible storage tools. With this flexibility can come problems
though. While all flash memory compatible devices share a few common
traits like a FAT file system to write to the card, they can differ vastly in
terms of expectation and execution. If you routinely shuttle your storage
devices between an array of different electronics, you may be setting yourself
up for future problems
The file system on your typical Windows XP computer is a robust thing, well
equipped to handle the complexities of reading, writing and erasing data on a
small piece of portable flash memory. The file system on your three year
old digital camera? Not so much... Simple devices like this want to be
able to write images to a storage device, read images off the same device and
erase them when necessary. They may not deal well with unsupported files,
data which has been added by other devices and other abstractions.
Wear and Tear
As mentioned above, flash memory has a finite lifespan measured in erase and
write cycles. That is to say, a specific block of NAND memory can only be
written to and erased x number of times before it fails to reliably store
data. In modern flash devices, this number generally extends to millions
of operations, and longevity is further ensured by an algorithm built into the
supporting circuitry of the memory that forces data to be written evenly across
the available memory blocks, preventing one area of memory from becoming more
'worn' and failing faster. Supplementing this is another system which
ensures that 'worn' sectors are mapped out of the grid of available memory,
similar to the method used to deal with bad sectors in hard disk drives.
Flash memory can and does wear out though. While a
typical USB drive or memory card should last years or decades of typical use,
exposing flash media to more read-write intensive operations like running an operating system or hosting applications
premature wear and tear and the eventual failure of the device.
Many flash memory devices are even more susceptible to the physical wear and
tear which comes with constant use. Devices like USB flash drives are
handled and used continuously, and are often not made to take much abuse.