Mac OS X: fsck reports benign errors when journaling is turned on
You can safely ignore some errors that fsck reports when journaling is enabled.
Note: This document applies to Mac OS X 10.3.9 or earlier.
Below is a list of errors that fsck reports that you can safely ignore when using journaling:
"Volume bitmap needs minor repair"
"Invalid volume free block count"
Note: The volume free block count is a type of cache of the real information stored in the volume bitmap, and the count being off does not mean your volume is damaged in any way. An incorrect volume block count message (block count changed from X to Y) is an example of this type of message.
"Volume header needs minor repair"
"can't locate IOPlatformMonitor"
"Incorrect block count for file"
Note: In the case of this message, you can erase the file and restore from the most recent backup if needed.
This article has been archived and is no longer updated by Apple.
Each of the messages above is benign, and indicates no damage to the file system. You may safely ignore them.
With a journaled volume you do not need to start up into single user mode. When a volume is made available to the file system, the journal is replayed and the file system brought up to a consistent state. If you do run fsck, it is best if you use -n and -f flags so that it will not actually modify the volume. Options explanation from fsck man page (short for manual page):
-n Assume a no response to all questions asked by fsck except for 'CONTINUE?', which is assumed to be affirmative; do not open the file system for writing.