On reboot a check will be made to determine whether a disk needs to be checked for errors. This will usually be after every fixed number of reboots or after a fixed amount of time. The fsck is run and can take some time.
On login we might see a message like:
*** /dev/sdc1 will be checked for errors at next reboot ***
On belinos I have been seeing this message for some time  and yet the disk is not checked on a reboot.
Note that a check can be triggered on the root partition if there is a
forcefsck in the root of the partition. For other
partitions, we can unmount the partition, do fsck, then remount it.
/var/lib/update-notifier/fsck-at-reboot contains the
message re file systems requiring reboots. It is updated by
Here’s an example of what I did manually:
gjw@belinos: $ sudo dumpe2fs -h /dev/sdc1 | grep -i mount dumpe2fs 1.42 (29-Nov-2011) Last mounted on: <not available> Default mount options: (none) Last mount time: Sun Aug 19 14:53:23 2012 Mount count: 86 Maximum mount count: 36 gjw@belinos: $ sudo umount /dev/sdc1 gjw@belinos: $ sudo fsck -y -c -f /dev/sdc1 fsck from util-linux 2.20.1 e2fsck 1.42 (29-Nov-2011) Checking for bad blocks (read-only test): 11.90% done, 9:13 elapsed. (0/0/0 errors) /dev/sdc1: Updating bad block inode. 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/sdc1: ***** FILE SYSTEM WAS MODIFIED ***** /dev/sdc1: 131/18317312 files (0.0% non-contiguous), 66340569/73262416 blocks gjw@belinos: $ sudo mount /dev/sdc1 gjw@belinos: $ sudo dumpe2fs -h /dev/sdc1 | grep -i mount dumpe2fs 1.42 (29-Nov-2011) Last mounted on: <not available> Default mount options: (none) Last mount time: Sun Aug 19 17:02:47 2012 Mount count: 1 Maximum mount count: 36 gjw@belinos: $ sudo /usr/lib/update-notifier/update-motd-fsck-at-reboot
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