FSCK_CS(8) System Manager's Manual FSCK_CS(8)

fsck_cs — verify and repair CoreStorage logical volume groups

fsck_cs -q device ...

fsck_cs -p device ...

fsck_cs [-y | -n] [-x | -g] [-l logfile] device ...

The fsck_cs utility verifies and repairs CoreStorage logical volume group metadata.

The device parameter(s) should be path(s) to the "raw" (character special) disk device(s) such as /dev/rdisk1s1 that constitute the CoreStorage logical volume group. If you specify a "non-raw" (block special) path such as /dev/disk1s1, or just the disk name such as disk1s1, it will automatically be converted to the corresponding raw disk device (/dev/rdisk1s1).

The options are as follows:

Performs a "quick" check and indicates if any corruptions were found via the exit status. In this mode stale MLV segments are not checked, nor is proactive MLV mirror scrubbing performed.
Operates in "preen" mode. MLV mirror blocks are repaired where necessary. Newer transactions may be invalidated to force a roll-back to an older, but consistent, filesystem state.
Causes fsck_cs to assume "yes" as the answer to all questions. In other words, always attempt to repair any errors that are found.
Causes fsck_cs to assume "no" as the answer to all questions. In other words, never attempt to repair any errors that are found.
Causes fsck_cs to produce its output in an XML-like (plist) format. This option is used when another application with a graphical user interface (like OS X Disk Utility) is invoking the fsck_cs tool and processing the output.
Causes fsck_cs to produce its output in GUI-compatible form. This is similar in usage to the -x option.
logfile
Reproduce all console output, as well as additional status and error messages, to the specified file.

Alternatively device can be specified as the UUID of the CoreStorage logical volume group or as the name of a CoreStorage-hosted logical volume within that group, causing fsck_cs to derive the constituent raw device(s) from the IORegistry. In these cases you must indicate what object is being supplied to identify the logical volume group:

the component CoreStorage physical volume(s) directly
the CoreStorage logical volume group (as a UUID)
a CoreStorage logical volume (as a device name)

The fsck_cs utility exits with 0 if no corruption was detected or if all corruptions were repaired, and with >0 if any unrepaired corruption remains.

fsck_cs does not perform an exhaustive validation, nor is it able to fix many of the inconsistencies that it does detect.

The fsck_cs utility first appeared along with CoreStorage in OS X 10.7.0.

July 22, 2011 OS X