Most file systems rely on full structural verification by the fsck utility as the only means to recover from a system failure. For large disk configurations, this involves a time-consuming process of checking the entire structure, verifying that the file system is intact, and correcting any inconsistencies. VxFS provides fast recovery with the VxFS intent log and VxFS intent log resizing features.
VxFS reduces system failure recovery times by tracking file system activity in the VxFS intent log. This feature records pending changes to the file system structure in a circular intent log. The intent log recovery feature is not readily apparent to users or a system administrator except during a system failure. By default, VxFS file systems log file transactions before they are committed to disk, reducing time spent recovering file systems after the system is halted unexpectedly.
During system failure recovery, the VxFS fsck utility performs an intent log replay, which scans the intent log and nullifies or completes file system operations that were active when the system failed. The file system can then be mounted without requiring a full structural check of the entire file system. Replaying the intent log might not completely recover the damaged file system structure if there was a disk hardware failure; hardware problems might require a complete system check using the fsck utility provided with VxFS.
The mount command automatically runs the VxFS fsck command to perform an intent log replay if the mount command detects a dirty log in the file system. This functionality is only supported on a file system mounted on a Veritas Volume Manager (VxVM) volume, and is supported on cluster file systems.
fsck_vxfs(1M) manual page and
mount_vxfs(1M) manual page.
The VxFS intent log is allocated when the file system is first created. The size of the intent log is based on the size of the file system - the larger the file system, the larger the intent log. You can resize the intent log at a later time by using the fsadm commnad.
fsadm_vxfs(1M) manual page.
The maximum default intent log size for disk layout Version 7 or later is 256 megabytes.
See Intent log size.