A soft update is a method used to keep computer file systems correctly aligned and consistent, especially after a crash that can throw file systems into chaos. There are similar methods for ensuring consistency after a crash, but most methods concentrate on duplicating the files; soft updates focus on making sure all the files are where they should be. When a crash does happen, these updates will do nothing to keep information from being erased, but the file systems should not lose their overall alignment. One problem with this technique is that, if a crash occurs when a soft update is being performed, any information that was moved may become corrupt.
Sometimes a computer crash may be a simple problem that can be fixed by the user restarting the machine; there will be no file system problems or loss of data. While this is ideal, larger computers and servers often experience problems with the file systems becoming misaligned. This means the systems will not know where files should be, which can lead to largely corrupted data that are difficult to retrieve. Soft updates work to make systems consistent even during such a situation.
A random computer crash is a common fear among computer users, especially for businesses and large entities, so there have been many methods created to reduce the damage of a crash. When it comes to maintaining file systems, most methods try to solve the problem by duplicating all the files found in the systems prior to the crash, like a backup. With soft updates, the files are not only backed up, but so is their position. This can help keep the systems from becoming corrupt, because they will remember where the files should be.
While soft updates may reduce the potential damage of a crash, they cannot entirely erase the risk. A crash is still capable of erasing some or all of the data in a computer or server. Some files may be saved through soft updates but, if the files were not archived, they may be lost forever.
A problem with soft updates is that they can cause the problem they are meant to avoid. When soft updates are changing around the file systems, many files are being moved and their positioning may not be concrete. If a crash occurs at this point in the process, the positioning will not be saved and the loose data may be corrupted and lost. This can usually be fixed, but the resolution often takes hours to perform.