With transaction logging and recovery, NTFS guarantees that the volume structure will not be corrupted, so all files remain accessible after a system crash. However, user data can be lost because of a system crash or a bad sector.
The NTFS file system implements a recovery technique called cluster remapping. When Windows NT returns a bad sector error to the NTFS file system, NTFS dynamically replaces the cluster containing the bad sector and allocates a new cluster for the data. If the error occurred during a read, NTFS returns a read error to the calling program, and the data are lost. When the error occurs during a write, NTFS writes the data to the new cluster, and no data are lost.
NTFS puts the address of the cluster containing the bad sector in its Bad Cluster File so the bad sector will not be reused.