Recovering Data from Flash Memory
The amount and importance of data which is stored on flash memory increases every day. With the price-per-gigabyte dropping it USB flash drives as well as memory cards (CF, SD, xD, etc.) have become a great way to store and transport large amounts of data. With an increased reliance on flash storage, the recovery of data from flash drives has become an important topic as well.
Flash drives are a very specialized piece of equipment but once you understand a few basics, they are a lot less mysterious. Flash drives use the FAT file system- USB memory keys generally use FAT-32 while memory cards (like those in a PDA or camera) use FAT-16. Almost all operating systems are compatible with the FAT file structure which is the reason why flash drives are almost univerisally compatible. Because they use FAT, all flash storage products have to use Master Boot Record, Boot Sector, and File Allocation Table (which exists in duplicate). These tables are composed of a list the files on the device, as well as a number of details, like their size and where they exist on the memory. Any damage to the table can make the data on the drive practically useless, which is why two exact copies of the drive exist.
There are a number of ways in which the information on flash devices can be compromised. The most obvious with a device this small is some sort of physical damage. While this is not likely, there is little that the home user can do about this except to send it to a data recovery specialist and cross their fingers. The way in which most flash drive's data is compromised happens when the device is prematurely removed from a computer. This means that the data is not fully sent and the file allocation table has not had a chance to update. Finally these devices are very easy to lose. If this is the case the data cannot be recovered, but it pays to make sure you have a security program installed so that your data cannot be accessed without a password.