Flash Memory Card Data Recovery Explained
We use memory cards everyday. Digital cameras, MP3 players, memory sticks, and other portable devices use some kind of flash memory: compact flash card (CF card), Secure Digital card (SD card), xD card, USB memory stick, or even Solid State Disk (SSD). This kind of memory is cheap, offers high storage capacity and needs power only for reading and writing. Sounds like an ideal memory type. It is but has some limitations. Imagine coming home from a long trip and connecting your expensive digital camera to the computer. There are no images! In such occasions you will soon become familiar with digital camera data recovery and portable media data recovery.
What Is Flash Memory?
Flash is kind of semiconductor non-volatile memory that uses cells to store data bits. It was invented in the 1980s and since then it has evolved into modern and reliable memory. Recent flash memory cards can store gigabytes of data—upper limits are still increasing and there is no sign of any stop. And while capacities are increasing prices are decreasing. This further contributes to the usage of flash memory in more and more electronic devices.
How Memory Cards Work?
Memory cards are electronic devices which have at least two parts: interface and memory. Memory part usually consists of one or more flash chips which store the data. Interface electronics acts as a bridge between memory chips and computer (or any other device using memory card). Interface is standardized and defines memory card type:CF card, SD card, xD card, etc. USB card readers are additional bridge between memory card and computer which present memory card as a disk drive which simplifies accessing cards with the computer.
Memory cards use file system like hard drives. It can be FAT, FAT32 or NTFS. Such file systems provide an elegant and compatible way to share files between computer and portable electronic devices.
What Kind Of Problems With Memory Cards Can We Expect?
Although memory cards are reliable they are still electronic devices which can fail. The interface electronics can fail preventing us from accessing memory chips and memory chips themselves can also fail. In addition to memory card electronics there is also a connector which enables us to easily insert card into card reader or digital camera. This means that we can remove memory card at any time. This may sound simple but it is not. If we remove the card while it is processing write requests we will disconnect power and therefore switch off all card electronics. This may cause the data to be only partially written to the card. And it is very likely that not only the file we have interrupted writing will be inaccessible, also the whole file system on the card may be corrupted. This is because for each file we write to any file systems we also need to update tables which define where files are located. If these tables contain wrong information we can no longer access or files.
How To Recover Data From Memory Cards?
There are two types of broken memory cards. We may have a working card where only file system is corrupt and this prevents us from accessing individual files. The other type is when there is a problem with the card electronics. With such failed memory cards you can not do much. If you really need the files it is best to contact find a data recovery service that deals with memory cards. They will be able to open it and restore the data. Learn how how is data recovered from flash memory devices.
However, if the card has only corrupted file system then you can try a do-it-yourself method first. Since the memory card is seen as an external disk drive you can use “ordinary” data recovery software used to recover data from hard drives. If you don't have such software simply google for it. You will find plethora of paid and free tools. You can also look for special memory card data recovery software (or portable media data recovery software) which has some additional features.
Data recovery software will analyze your card and offer actions to restore file system data. You will be also able to see deleted files and “undelete” them. Some advanced image recovery software will also offer you the possibility to repair damaged images. Since they are saved in one of standard formats (raw, jpg, tiff, png) it is easy to repair corrupted file. Of course, there is no guarantee that the image will still look like the original. Image recovery tools only help you to recover what is possible.
How To Properly Use Memory Cards?
The first rule to properly use memory cards is the following: NEVER remove, disconnect or turn power off of memory card while it is used for reading or writing. If you do this it is very likely that you will corrupt the data on the card and even damage the memory card. Always make sure you can safely remove the media. Computers provide a “safe hardware remove” utility and for other electronic devices the best way to safely remove the media is to properly switch them off.