Practical Memory Card and USB Flash Disk Data Recovery

All removable media like flash drives, USB disks, pen drives and flash memory cards are based on the same technology: flash memory. This is semiconductor memory that can be programmed with data and for this operation it needs power, but after we disconnect the power the data stays there. Solid state disks (SSD) also fall into this category of storage devices. The main difference is in the electrical and mechanical interface used to connect to various devices including computers (USB, Compact Flash, SD, SATA, FireWire, etc.). Each flash memory media has two electronic devices: interface electronics (or controller) and flash memory. Interface electronics acts as an interface or bridge between memory chips and outer world: it connects with computer, digital camera or any other device and writes to or reads from the flash memory. Removable media can fail. Flash drive or memory card data recovery is possible in most cases. Flash USB data recovery is not complicated and in some cases we can do it ourselves. Here we will describe methods used by professional data recovery companies.

Problems with memory cards and pen drives can be divided into two groups. In the firs group are problems related to file system and data corruption—the electronics works, only the data is missing or corrupted. The second group contains problems where the removable media can not be accessed—there is some problem with the electronics. The first group of problems can (at least in most cases) be solved with data recovery software. Since the media is accessible and it is visible as a disk drive, we can apply standard procedures to recover file system or files. This is relatively simple, we only need disk data recovery software and some knowledge about file systems.

Data from memory cards or USB disks with failed electronics can also be recovered, we only need to open the media and examine individual electronic components. It is very likely that the problem is in the interface electronics. Since it is exposed to external elements it can easily be damaged. Static electricity, electric shocks, excessive heating or any other influence can damage the controller (interface electronics). But the data is still in the flash memory chips. In order to access the data we need somehow to connect the computer to the flash memory. This operation requires two steps: physical removal of the chips and reading them with flash memory reader. To do this we need some not-so-expensive equipment and a little practice. For example, to get the data from a broken pen drive we need to perform a simple USB flash data recovery operation.

Flash memory readerFlash memory drives contain a small printed circuit board where all the chips are soldered. Physical removal of one or more flash memory chips requires soldering station suitable for surface mount devices. We need to gently desolder all memory chips. This is not a task for beginners. In order to deal with small and sensitive SMD components we need a lot of experience and patience. With wrong approach we can easily damage the chip by overheating it or mechanically breaking pins. Once the flash memory is separated from the portable media we can proceed with data reading.

To read memory chips we need special flash reader. This device will replace the damaged controller (interface electronics) and will allow us to read the data and save it to the computers. Usually such flash memory readers come with a USB interface and dedicated easy to use software. However, it is not enough to read the chips. We will only get a raw flash drive data that was stored in the integrated circuits. The memory card interface electronics contains a controller which takes care not only for reading and writing but also determines memory addresses or data locations . We don’t know how this data was organized and stored. Therefore we need some additional algorithms and data recovery tools to interpret this raw data in order to recover the original file system. Fortunately, many flash readers include also some data recovery tool to solve this problem. They can analyze the data and transform it into the original disk as it was once present in the broken portable media. And once we can access the disk we can also recover deleted files and folders.

This approach is what commercial data recovery companies do. Flash disk or memory card data recovery is not as complex as hard disk drive recovery but still needs some tools and knowledge. Now it is clearer why memory card and USB flash disk data recovery is cheaper than other data recovery services. But even if the recovery tools needed are not expensive, we need to know how to handle sensitive electronic components and how to recover corrupted file system. For some this represents a big obstacle, for others it is a simple operation.


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