fsck – Is Forcing fsck Safe?

From the e2fsck man page :

"Note that in general it is not safe to run e2fsck on mounted filesystems. The only exception is if the -n option is specified, and -c, -l, or -L options are not specified. However, even if it is safe to do so, the results printed by e2fsck are not valid if the filesystem is mounted. If e2fsck asks whether or not you should check a filesystem which is mounted, the only correct answer is ''no''. Only experts who really know what they are doing should consider answering this question in any other way."

So if you check a mounted FS with fsck even using the -n option the result may be not valid at all. Don't check mounted filesystems. Use a Live-CD/Live-USB.

If you don't check the filesystem while it is mounted, I don't understand why you need to use touch /forcefsck you can just unmount it and fix it. But if it is the case and after a fix your FS still have errors then you can consider using :

e2fsck -cy /dev/sda5

That will fix an hard drive related issue called bad blocks you may have (this will take a long time).

If you want to check a mounted filesystem, I don't know how to proceed but I think you should create another question.

To run fsck on your harddrive you need to boot a liveCD and then run the commands with your harddrive partitions as the target.

"There is no /forcefsck file in my root"

-You need to create the file, it is just a blank file so run sudo touch /forcefsck and fsck will check your drive next time your reboot.