Linux: Skip or Bypass a Fsck

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.

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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

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15 comments… add one
  • Sam Watkins Mar 9, 2012 @ 5:04

    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

    http://sam.nipl.net/code/nipl-tools/bin/fsck-convenient

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

  • Lince Toddle May 3, 2012 @ 17:38

    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?

  • helpful Jan 7, 2016 @ 1:03

    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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