When I did the RAID 10 test, I didn’t add the “UUID” information into /etc/mdadm.conf file initially. After I reboot the system, it was unable to boot.
I inputted the password and entered the maintenance mode. I tried to delete the line I had added from the /etc/fstab file, but the file is in real-only mode and I could not to modify it. After searched the solution in the internet, I did the following four steps. The problem had been solved.
1. Check the filesystems.
(Repair filesystem) 1 # fsck –a
… …
fsck.ext4: No such file or directory while trying to open /dev/datavg/datalv
… …
2. Remount the root file system and make it writable.
(Repair filesystem) 2 # mount –o remount,rw /
EXT4 FS on dm-0, internal journal on dm-0:8
3. Edit the /etc/fstab file, delete the line I had added, save and quit.
(Repair filesystem) 3 # vi /etc/fstab
4. Reboot the system.
(Repair filesystem) 4 # reboot
Kezhong's Weblog 
IT DOESN’T WORK….
By: Zeeshan on July 31, 2009
at 2:11 am
Did you do the first step(check file system)?
By: kezhong on July 31, 2009
at 1:31 pm
tried it but it doesnt allow the remounting ….
By: Zeeshan on July 31, 2009
at 2:12 am
As it couldnt able to find the editng file…
By: Zeeshan on July 31, 2009
at 2:13 am
Worked like a charm! Thanks a lot!
By: smsman on May 23, 2010
at 7:05 pm
It helped me to remount the / file system.
Thanks a lot !!!
By: Lokesh on October 22, 2010
at 1:54 am
Very smart solution sweet kiss for you
By: Anonymous on December 14, 2010
at 1:13 am
not sure what to do…now when i rebooted i get this message
error: unknown filesystem
grub rescue> _
now what?
By: oduinn on January 16, 2011
at 6:10 pm
Thanks, It worked for me.
By: Huzi on May 5, 2011
at 1:17 pm
the system we’re installing can’t boot up, until we read this post… thank you…
By: cabaihidup on June 17, 2011
at 7:26 am
man, u r a life-saver! i was doing some test on cryptsetup and all the suddent the CentOS 6.2 is not booting again… with your simple steps, I was able to edit the fstab and comment out the bad device and it’s booting again. Thanks so much!!! =)
By: ks on June 1, 2012
at 1:18 am
same pinch :D i’m also doing testing on cryptsetup & faced the same problem!!
By: raj on July 23, 2012
at 6:39 am
yes it’s working good thanks
By: john on June 26, 2012
at 11:15 am
good article
By: Winanjaya on July 3, 2012
at 9:26 pm
thanks it worked for me……………..an excellent answer..
But when I m trying to mount .img file its saying “operation not permitted”
even when i am trying to assign full permission to .img file its saying
“chmod: changing permissions of `/home/test1.img’: Operation not permitted”
By: karan on July 7, 2012
at 7:06 am
Thanks, it worked for me.
By: jonyen on July 31, 2012
at 3:33 pm
Thanks you just saved me from a very very late night
By: Anonymous on August 6, 2012
at 11:44 pm
This helped me to solve an hour of search … thank you so much
By: Anonymous on April 30, 2013
at 7:38 am
Thank you Kezhong! It worked perfectly. Many other sites produced relatively unsatisfactory results.
By: Anonymous on July 19, 2013
at 1:24 am
Nice.
I edited fstab trying to mount an external drive, mucked it up, and couldn’t repair. This did the trick for me, thank you!
By: Just A Dog on October 11, 2013
at 4:29 pm