Logical failure
A logical failure is a problem in the file system, the partition, or the files themselves, while the storage hardware still works.
The disk can spin, identify itself, and read sectors. What is broken is the map that says where the files are, or the files have been deleted, formatted, or partly overwritten. People often still say the drive has failed, because the files will not open.
How does a logical failure happen?
A format, a deleted partition, an update that was interrupted, malware that encrypts files, or a file system that no longer agrees with itself can all leave the hardware healthy and the data unreachable through the computer.
Why does the hardware still matter?
One drive can have both a logical and a physical fault, and reading a logically damaged volume still means asking the device for sectors. If the device also has a physical failure, those reads can make that fault worse.
What should you do if files have vanished but the drive sounds normal?
Stop writing to that disk. Do not reinstall the operating system onto it, and do not save new files there. New data can occupy the space where the missing files still sit. A sector-by-sector disk image, taken while the drive still reads, keeps a copy of that space before anything else is written.
What might you notice?
- The drive is detected, but a folder is empty or missing
- The computer asks to format the disk
- A message says the file system is raw or corrupt
- Files were deleted, or the disk was formatted
Related terms
Common misconceptions
If the computer can see the drive, is the failure only logical?
Not necessarily. A drive can report its name and still have weak heads or bad sectors. Showing up in the computer is not the same as being healthy enough to read every sector.