That’s the main reason why people like to use SanDisk CF cards for their cameras and other digital devices. See this translation table as a 'FAT' for the firmware, only this table is used by firmware to map LBA addresses to actual NAND pages.Posted to File Recovery Tips by Jonkman on Apr 3, 2022Ĭompared with other memory cards, like SanDisk CF card give users a larger capacity to save files and it’s faster to read and write data. It is either unable to detect the NAND memory -or- NAND translation table is corrupt. It's an indication controller is working but in let's call it a safe mode. Typically physical capacity is decreased to MBs rather than GBs. In these cases dumping the NAND is almost always required. If card (whatever card, CF, SD etc.) is detected but physical capacity is incorrect: With regards to logical photo recovery software, often mentioned names are PhotoRec and Recuva, also free and very good is R-Photo made by the company that produces R-Studio which is used in many labs for logical data recovery. I use the Soft Center reader and software (called Flash Extractor). NAND readers are not overly expensive (but still too for a single case probably), it's the software that is needed to convert the raw dump to a logical image that is. It's the logical image reconstruction part that is most complex and time consuming. Ideally result is a coherent file system, however sometimes raw recovery is highest achievable. Using specialized software I then convert the dump to a logical file system using software that emulates the controller (or tries as good as it can) from which files can be recovered. If unable to repair I unsolder NAND chips and 'dump' them using a reader. If a working and matching donor board is available, often NAND chips can be transferred to donor PCB. Some times it's enough to reflow the solder under the NAND chips. If I can spot defects I'll try repairing them, and if successful I can now access the card. Open the 'case' and inspect the PCB using multimeter and microscope. If I am asked to handle a case like that I: Verify with a different reader, if card still isn't recognized then in general this can't be recovered using software. "The card is similarly unrecognisable on my computer CF card reader."īasically for software to work, the card has to be detected in Windows Disk Management with correct capacity. And it automatically works out how much it can actually read successfully between the failed/damaged sectors. You can keep re-running it to build up an image of the disk from whatever is readable with the various techniques. retries, which can be good on magnetic/optical disks) to fill in the gaps. If the CF card wasn't having such serious failures, I think it'd be possible with PhotoRec alone, as others have suggested.ĭdrescue's main utility seems to be the way it lets you get as much of a disk as is available, and use various techniques (e.g. I imagine this might be a pretty special case, but in any case I've been able to piece most of the disk back together with ddrescue, using the -i option to skip the chunk where it fails, and otherwise read the sectors that work, to generate a new disk image file to use with PhotoRec. The problem I have is not only parts of the filesystem/files being unreadable, but when I attempt to read a specific part of the CF card, the disk stops responding entirely, which makes it quite difficult to import files off it. I'm currently in the process of using ddrescue to recover photos from a corrupt CF card (I believe hardware failure).
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