New technology file system journaling is used to help NTFS-formatted drives recover from power failures and other events. Activities are logged before they are performed, which helps the file system recover when it is brought back online.
Most actions performed on a hard drive take multiple steps. If a file is deleted, for example, the reference to the file must first be removed, and the space it occupied must be marked as available for writing. If the power fails between these steps, the file will no longer exist, but the space it occupied may be marked as unavailable. If the deletion is entered into a journal before any action is taken, the hard drive can recover quickly.
NTFS journaling is optional, and experts would sometimes recommend that users turn it off for better performance. Today, the benefits of journaling outweigh the small negative performance penalty. In addition, the speed difference when performing basic operations is minimal and will only become noticeable if the hard drive is being used as a server. Hard drives have become significantly larger over the years, and the extra protection provided by journaling allows computer users to know that they will be able to recover from most data corruption scenarios.