Why does fsck show corruption when running 'fsck -n' on a mounted device when the devices are clean?
Issue
- Issuing an
fsck -non a mounted in use device reports filesystem corruption, but when running afsckwhen the device is unmounted it reports the device as clean. - The following types of errors are encountered when running a
fsckon a mounted filesystem:
# fsck -n /dev/mapper/VolGroup-lv_test
fsck from util-linux-ng 2.17.2
e2fsck 1.41.12 (17-May-2010)
Warning! /dev/mapper/VolGroup-lv_test is mounted.
Warning: skipping journal recovery because doing a read-only filesystem check.
/dev/mapper/VolGroup-lv_test contains a file system with errors, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Block bitmap differences: -2974075
Fix? no
Free blocks count wrong for group #90 (2630, counted=2629).
Fix? no
Free blocks count wrong (7702583, counted=7714667).
Fix? no
Free inodes count wrong (7285539, counted=7285465).
Fix? no
/dev/mapper/VolGroup-lv_test: ********** WARNING: Filesystem still has errors **********
/dev/mapper/VolGroup-lv_test: 103645/7389184 files (0.4% non-contiguous), 21826505/29529088 blocks
- However, when the device is unmounted an
fsckreports no problems:
# fsck -fy /dev/mapper/VolGroup-lv_test
fsck from util-linux-ng 2.17.2
e2fsck 1.41.12 (17-May-2010)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/mapper/VolGroup-lv_test: 103645/7389184 files (0.4% non-contiguous), 21826505/29529088 blocks
Environment
- Red Hat Enterprise Linux (RHEL)
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