Logical – Advanced Sector Level Hard Drive Failure
This describes a hard drive data recovery task where stored data has encountered corruption in very specific locations on the device. This corruption usually results in the system not booting, or in the file system not reporting file content as expected.
Data recovery in this type of case is a manual process and is labour intensive. It involves analysis of specific identifiable data structures at byte-level and manipulation/correction of specific binary values to correct the defect(s).
These types of data recovery tasks do not involve cleanroom handling, as the drives do not need to be physically opened. This is a particularly specialised type of recovery that requires forensic-level knowledge of filesystems.