this is the step that i done yesterday when my Centos fail to boot because of electricity problem.  this is for checking file system concurrency when ask by the system.

fsck /dev/sda1

please be sure to specify file system

fsck -t ext3 /dev/sda1 or

fsck.ext3 /dev/sda1

answer y for all question that came up, tryto use :

fsck -y /dev/sda1

once it has finished, remount file system : mount /usr/u02

read man fsck for further information.