Broken Memory

ZAR has been discontinued

After about twenty years, I felt ZAR can no longer be updated to match the modern requirements, and I decided to retire it.

ZAR is replaced by Klennet Recovery, my new general-purpose DIY data recovery software.

If you are looking specifically for recovery of image files (like JPEG, CR2, and NEF), take a look at Klennet Carver, a separate video and photo recovery software.

Bad Random Access Memory (RAM) chips will cause data loss, and recovery attempts require them to be replaced.

Faulty DIMMs will usually manifest themselves in spontaneous reboots, blue screens or program failures. Things of all sorts can happen when data that is read from memory differs from what was written to that memory. An implication is that some wrong data from memory will eventually end up being written to the hard disk.

A faulty memory page in a disk write cache will result in wrong data written to the drive. On top of that, the operating system will usually be unaware of data corruption. A "write miss" situation is also a possible scenario, albeit rare. A RAM malfunction can cause correct data to be written to an incorrect location on the disk, thus overwriting some other piece of data.

Soon after a memory chip goes bad, the logical structure of a hard drive starts to degrade, ending up in an unbootable system or an unmountable volume. The extent of damage varies, but most files are usually recoverable.

The key point here is: a bad memory chip must be replaced before attempting any repair. This is because:

Attempting to repair the disk in-place (using CHKDSK or Norton Disk Doctor) can cause additional damage. Attempting a read-only data recovery with ZAR tools is unlikely to damage the drive further, but may damage the target (good) drive during file copying.
Recovery can be safely carried out if you attach the damaged drive to another computer, but you must replace the broken memory before you bring the data back, otherwise you risk losing your data again.

Several memory testing tools are available, examples being GoldMemory and DocMem. They can reliably detect memory failures and we suggest using them when in doubt.