Linux: Skip or Bypass a Fsck

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Q. I know how to force fsck on the next reboot using /forcefsck file. But how do I skip or bypass a fsck on reboot? How to stop a FSCK from prompting or running automatically when rebooting server.

A. It is recommended that you run a fsck on reboot if required. Usually, system automatically determines if fsck required or not. Generally, fsck is run automatically at boot time when the system detects that a file system is in an inconsistent state, indicating a non-graceful shutdown, such as a crash or power loss.

Bypass a fsck using shutdown command

When rebooting the server use the following command
# shutdown -rf now
Above command will reboot the system and will not run auto fsck.

Set Linux kernel option by editing grub.conf / menu.lst

Open grub.conf or menu.lst (usually located in /boot),
# vi /boot/grub.conf
Find kernel line and put fastboot at the end of the kernel line. In the end it should look as follow:
kernel /vmlinuz-2.6.18-92.1.22.el5 ro root=LABEL=/ console=tty0 console=ttyS1,19200n8 fastboot

Skip fsck by updating /etc/fstab file

Finally, you can edit /etc/fstab file which, contains descriptive information about the various file systems. You will see two numbers at the end of the line for each partition, change the second number to a 0 (zero digit). This will have the system mount the partition but will not run a check when booting. The sixth field, is used by the fsck program to determine the order in which filesystem checks are done at reboot time. The root filesystem should be specified with a fs_passno of 1, and other filesystems should have a fs_passno of 2. Filesystems within a drive will be checked sequentially, but filesystems on different drives will be checked at the same time to utilize parallelism available in the hardware. If the sixth field is not present or zero, a value of zero is returned and fsck will assume that the filesystem does not need to be checked. Here is sample entry:

LABEL=/disk3		/disk3			ext3	defaults	0 0


Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.

15 comment

  1. Hi,

    We can permanently bypass fsck check on any filesystem using tune2fs command as follows:

    root@server[~]# tune2fs -i 0 /dev/sdb1
    tune2fs 1.35 (28-Feb-2004)
    Setting interval between check 0 seconds
    root@server [~]#

  2. Is the kernel parameter method (with grub/menu.lst) really valid?

    fastboot and forcefsck are not listed as valid kernel parameters,
    and I don’t know if it’s an ubuntu-ism, but neither my /etc/rcS.d/ nor my /etc/rcS.d/ include support these parameters.

  3. on my /etc/fstb
    line 1: proc /proc proc defaults 0 0
    line 2: /dev/sda1 / ext3 defaults,errors=remount-ro 0 1

    just change
    line 2: /dev/sda1 / ext3 defaults,errors=remount-ro 0 0

    it will pass checking the root partition

    it works for me

  4. This was helpful information, but I’m still stuck … the machine is shut down, and on boot fsck auto-runs and exits into a maintenance shell telling me to run it manually. In that process it also mounts the file system as read-only. When I attempt to run fsck manually it hangs and all I see is a black screen.

    1) can’t use the shutdown switch, since the machine is already off
    2) tried to modify the boot options in grub, but fastboot doesn’t do anything
    3) tried to modify fstab but it’s read only. Once I unmount the system (/dev/sda1), the device name no longer exists and I can’t mount it again as r/w

    How do I prevent fsck for running at boot time and mounting the fs as ro? This is on xubuntu (hardy) … oOr alternatively, how do I remount the fs as rw in the maintenance shell …. Help ….?

  5. Thanks this was just what I was looking for! I had a system that was stuck in a loop trying to fsck a bad hard drive. The fastboot option skipped the check and let me boot into the system to do what I needed.

  6. The first answer is so typical answer by linux people: never answering to the question and instead assuming the user is stupid. I I want to destroy my hard drive it’s up to me, no?

  7. Is there a way to disable timed checks but ensures all disks are checked after a critical failure? Fedora, force checks after a certain amount of days and/or remounts.

    However I would prefer to just reserve these checks if there is a valid reason for doing them.

  8. I would really like to do the FSCK but not manually. Is there an option to have it run through it automatically without dropping to a command line during boot?

  9. I decided to leave the auto-fsck in there, but write a program that warns me, when an auto-fsck is coming soon. Then I will have the opportunity to avoid it by running a manual fsck, e.g. before I turn off the computer at night.

    The script needs to run as root, so it can read the device info with tune2fs -l

    Running this from .profile or on X startup without output to xmessage isn’t too hard.

  10. Thanks for your hints – last question is quite interesting,
    well, in my case displaying an non-interactive splash screen
    that tells the user just to stand by could be a neat one.

    Also, periodical fscks could be run during shutdown instead?

  11. OK the ways and means of stopping a fsck from happening at boot time are a little bit more complex. A) most filesystems allow for tune2fs to modify parameters – one method of checking is “number of days since last check” and the other is “number of mounts since last check” – so you can choose the method in most cases. B) some filesystems will always run a fsck, mind you a quick one, whenever you try to mount a filesystem these are mostly the more modern filesystems. C) as indicated you can change things with fastboot or by modifying /etc/fsck either with grub or with a mounted “/etc/fsck” fs – which may require a ‘mount -o rw,remount /’. Different version of the LINUX kernel support different options – check out BSD versus LINUX versus AIX or Solaris. If you have a hotswap drive installed you may have complications – as a drive group with a hotswap may take some time (appearing to be locked up and non-responsive when in fact it is very busy laying down a new fs on the hotswap drive). The only case I know of where this caused a lot of problems was when someone had perforce assumed control of a hotswap drive and had partitioned it up and was running executables on it. Naturally when one of the real drives got sick the hotswap script took over – changed the fs layout but could not do much because the drive had active connections to parts of the disk. So it A) failed to do its job and B) the code that was running could no longer find its dependent code fragments so … watch out.

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