# man fsck

OPTIONS
       -a     Automatically  repair  the  filesystem  without any questions (use this option with caution). 

       -n     For some filesystem-specific checkers, the -n option will cause the fs-specific fsck to avoid attempting 
              to repair any problems, but simply report such  problems  to stdout.   

       -y     For  some  filesystem-specific  checkers,  the  -y  option will cause the fs-specific fsck to always 
              attempt to fix any detected filesystem corruption automatically.

       -f     -f option to fsck (Force checking even if the file system seems clean.)

# cat /proc/partitions 
# fsck -nf /dev/sda3    <- check
# fsck -f /dev/sda3     <-  fix

The -F flag means 'force fsck'.

# shutdown -rF now

# vgchange -ay VolGroup00
# fsck -f /dev/VolGroup00/LogVol00

1. Booting into Single-User Mode

   1. At the GRUB splash screen at boot time, press any key to enter the GRUB interactive menu.
   2. Select Red Hat Enterprise Linux with the version of the kernel that you wish to boot and type a to append the line.
   3. Go to the end of the line and type single as a separate word (press the Spacebar and then type single). 
      Press Enter to exit edit mode.
   

   or

   # init 1
   

2. check disk with mount command

   # mount
   

3. umount root partision and fsck

   # umount /
   or
   # mount -o remount,ro /
   or
   # mount -o remount -rn /
   

4. Check read only file system.

   touch /tmp/test.txt
   

5. start fsck

   # fsck /dev/mapper/VolGroup-lv_root