When nodes fail with the file system mounted, file system journaling allows fast recovery. However, if a storage device loses power or is physically disconnected, file system corruption may occur. (Journaling cannot be used to recover from storage subsystem failures.) When that type of corruption occurs, the GFS file system can be recovered by using the gfs_fsck command.
The gfs_fsck command must only be run on a file system that is unmounted from all nodes.