Defaulting to verify the image integrity before installing on desktop?

Sebastien Bacher seb128 at
Mon Nov 25 16:52:21 UTC 2019

(cross posting

Triaging ubiquity bug reports on launchpad, one of the most common
reason for failing installations is that the image/media used to do the
installation is invalid/corrupted. It shows in the log with such error
’SQUASHFS error: zlib decompression failed, data probably corrupt’

There is usually no user friendly explanation of what the problem is in
those cases, which means users just download the iso/write it/boot the
media and follow the steps and at some point get a random ubiquity error.
One recent example of such report
Since we don’t explain the issue nor recommend a solution it’s often not
obvious to user what is going on and what they should be doing.

In that context, what would people think of making the default choice on
the desktop liveCD to be ‘check & install’ and make the start of the
installer conditional to not having error on the media?

I’ve tried to get some data for the discussion and tested the ‘check
disk’ option on some configurations with an old/slow usb stick and a
recent enough cheap usb3 one

  * a 10 years old latitude with an i5 cpu (bios)
  * an old/slow inspiron11 (uefi)
  * a recent XPS13 (uefi)

The check takes between 1 minute and a bit less than 3 minutes,
depending of the configuration/media. (I didn’t measure the installation
time then but it’s significantly longer on any of the machines)

And as an extra data point, I recently booted a fedora 31 ISO to test a
bug and the liveCD menu default to check the media first there.

I think that the cost is reasonable and that it would avoid an awkward
experience that some of the new Ubuntu users are getting.

What do others think? Should we default to check the media before
booting the ISO? (And if so do we need to ensure the menu still provide
a way to skip the testing (we should at least for automaticall


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