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The HTFS, EAFS, AFS, and S51K filesystems rely on the full structural verification of the fsck(ADM) command as the only means to recover from a system failure. The fsck command for these filesystems checks the entire structure and verifies that the filesystem is intact and corrects any inconsistencies that are found. For large disk configurations, this process can be time-consuming. See ``Solving filesystem problems'' for more information.
The VxFS filesystem provides recovery only seconds after a system failure by using a tracking feature called ``intent logging''. Intent logging is a circular logging scheme that records pending changes to the filesystem structure. These changes are recorded in an ``intent log.''
Upon recovery from a system failure, the VxFS fsck command scans the intent log, nullifying or completing filesystem operations that were active when the system failed. The filesystem can then be mounted without completing a structural check of the entire filesystem. Except for the fact that VxFS filesystem recovery is completed in a few seconds, the intent log recovery feature is not readily apparent to either the user or the system administrator.