TOC · Work · Data Recovery

Data Recovery from Damaged Devices

If you are in doubt about physical health of your device (error messages, slow responding, extraneous sounds, there was a hit, fall etc.) it is highly recommended to address to specialists having specialized equipment. Any further work with the disk (including even starting up) may worsen the problem and cause complete inability to recover data. So any further attempts are at your own risk. Anyway it is possible only if the software can access the device (contents are readable), and device size is detected correctly (info on incorrect device size).

Software Bads

Some errors may be due to external reasons: bad contacts, unexpected power loss or disconnection, etc. If a sector is not completely or incorrectly written then the device reports an error when reading such sector even there is no physical damage (software bad). The device is working normally excepting errors when reading several sectors. In such case you should fix the problem source (check if PCB contacts are oxidised, replace wires, etc.) and continue accessing the device safely if the doings don't become worsen (some software bads may still remain). Of course this does not apply to cases where a hit was, the device is responding slow, etc. Anyway it would be safer to make a copy of the entire device before continue recovering.

Device Cloning

It is highly recommended to first clone the damaged device and to work further with the copy.

During data recovery there may be multiple disk access retries: software usually scan the entire device, then again analize some structures on the disk, then read data again during actual recovery; different settings and software may also be tried. This causes reading the device again and again damaging the problem device more and more. Making a sector-wise copy (clone) eliminates this problem, the damaged device is read only once.

In DMDE you may use the tool Copy Sectors to make the device clone.

Special Environment and Settings

Normally OS may also work actively with a device damaging it more, interfere while working with it, as well may write unwantedly on the source disk (see also the section "Installation"). So you should choose a more suitable OS, prepare the device, configure the parameters.

It is better to use direct access in DOS. However there is a number of restrictions in DOS so the way is suitable primarily to create a clone when devices are visible in IDE compatible mode. Linux (and especially "Live" images) don't work actively with device partitions until you mount them so there are no special settings. Regarding Windows it is highly recommended to use special "Live" images, even more special environment like WinFE which don't work with device partitions until you mount them. It is also recommended to use IO SCSI mode as it is more fast and soft.

To completely prevent an OS from working with the device partitions you may temporaryli "switch off" a partition table (e.g. for MBR disk it is enough to change the signature 55 AA in the lst two bytes of the disk starting sector). In DMDE you may use commands MBR Off / GPT Off in the Partitions window, then Apply, and restart the OS or reconnect the disk. Later you may similarly "turn on" the partition table on the disk or its copy if it is necessary.

If Cloning is Impossible

Sometimes the device state does not allow entire cloning. Full copy may take an unreasonable time but you need to recover only some important files. In such case you may try data recovery without performing a full scan.

DMDE allows opening volumes and finding some files without preliminary full scan. You may try opening the volume if it is visible in the window Partitions just after selecting the device. You may also try opening volumes as soon as they appear in the results of Full Scan without waiting its completion. Make sure to Save scan results to avoid future rescanning in case of some failure. Open the volume and recover the most important files first and check if they can be opened/played.