3

Downloaded 20.04 and created a USB using Rufus under windows 10. A disk check seems to be triggered at each launch of the USB disk (using it as a live disk). Is there a way to stop this from happening?

5
  • 3
    Yes, easily. The instructions are on the screen during the check. You should be able to cancel it at any time during the check. You cannot, however, permanently disable it (it's a read-only fliesystem). The check was added to eliminate one of the most common causes of failed installs for new users - a corrupted or incomplete .iso download.
    – user535733
    Apr 24, 2020 at 13:24
  • 1
    If I do not hit ctl-c immediately the check goes on for about five minutes. Very irritating, I think this must be a bug, nobody would do this on purpose. It even runs on persistent USB drives, they are not read only. Apr 24, 2020 at 13:54
  • 2
    I think the problem is that cancelling the check might only happen after the current file has been processed, and since 20.04 contains a 2 GB casper\filesystem.squashfs, if you try to cancel while that file is validating,you're going to have to wait until those whole 2 GB have been read, which could indeed take minutes on a slow drive...
    – Akeo
    Apr 24, 2020 at 19:57
  • 1
    @Akeo:Sounds right. If I boot with fingers hovering above ctl and c and act the instant "Checking disks" appears, checking is cancelled. Congratulations on getting Rufus persistence working on 20.04. Now if you could just get rid of the try/install screen on persistent installs. As I recall it is just a matter of tweaking syslinux.cfg. Apr 25, 2020 at 2:46
  • @Robert Levy: Bug Report filed, do you have anything to add? bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/… Apr 28, 2020 at 6:45

2 Answers 2

3

Removing Disk Check on Persistent USB's

The command line option fsck.mode=skip can be used to skip the disk check.

The line Checking disks: 0% complete will still come up but fsck will not be run, nor will boot time be increased.

mkusb After the Persistent USB drive is created, open /boot/grub/grub.cfg as root.

  • Add fsck.mode=skip to the Persistent menuentry thus:

    linux ($root)/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed maybe-ubiquity fsck.mode=skip quiet splash persistent ---

  • Newer versions of mkusb already include this fix.

  • If you also wish to remove the Try Ubuntu / Install Ubuntu screen delete "maybe-ubiquity".

UNetbootin After creating the boot drive, open /boot/grub/grub.cfg as root.

  • Add fsck.mode=skip to the first menuentry for (UEFI boot mode).

  • Open syslinux.cfg as root and add fsck.mode=skip to the default menuentry for (BIOS boot mode).

Rufus After creating the boot drive, open /boot/grub/grub.cfg as root.

  • Add fsck.mode=skip to the Default menuentry for (UEFI boot mode).

  • Open /isolinux/txt.cfg as root and add fsck.mode=skip to the "Try Ubuntu without installing" menuentry, (for BIOS boot mode).

The Try Ubuntu / Install Ubuntu screen can be removed from BIOS boot by overwriting syslinux.cfg with:

default persistent
label persistent
  say Booting an Ubuntu Persistent session...
  kernel /casper/vmlinuz
  append  file=/cdrom/preseed/ubuntu.seed boot=casper persistent initrd=/casper/initrd quiet splash noprompt --

The Try Ubuntu / Install Ubuntu screen can be removed from Rufus UEFI boot by removing "maybe-ubiquity" from /boot/grub/grub.cfg. . . .

Edit 20200524: The above workaround is no longer needed.

This bug was fixed in the package 'casper - 1.447', as announced in: https://bugs.launchpad.net/ubuntu/+source/casper/+bug/1875548

Run:

sudo apt-get update
sudo apt-get install -y casper

(I am still testing the fix, It does not seem to be working yet).

2
  • Thanks to brian-murray for fsck.mode=skip Apr 29, 2020 at 7:38
  • If you're using cubic you can change the boot grub.cfg in the "boot" tab at the top, just before you actually create the ISO. Feb 2, 2021 at 23:38
0

If you do not need this USB to install Ubuntu...

Consider doing a Full install to USB, It does not suffer from this irritating disk check problem when booting.

A Full install USB and a Persistent install USB both save data and installed programs after reboot.

Comparison between Persistent and Full install USB

Advantages of a persistent install:

1) You can use the persistent pendrive to install Ubuntu to another computer.

2) A persistent install takes up less space on the pendrive.

3) You can reset the pendrive by overwriting the old casper-rw file with a new one.

4) The install to pendrive takes less time.

Advantages of a Full install:

1) You can update and upgrade.

2) If you have problems or wish to modify, the solution is the same as with an internal install, (You can ask for help in these forums).

3) No ugly startup / install screen.

4) Better security, you can use full encryption

5) You can use proprietary drivers.

6) Hibernation works.

7) A persistent install is limited to a 4GB casper-rw and a 4GB home-rw persistence file, to get more persistence requires persistence partitions. Once casper-rw is full, the drive will not boot.

8) Faster boot, no automatic disk checking.

9) You can run VBox and use virtual machines.

Note that once booted, both methods run at about the same speed.

Full Install Method

One method for creating Full install USB: How to Create a Full Install of Ubuntu 20.04 to USB Device Step by Step

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .