Defaulting to verify the image integrity before installing on desktop?

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Defaulting to verify the image integrity before installing on desktop?

Sebastien Bacher

(cross posting https://discourse.ubuntu.com/t/defaulting-to-verify-the-image-integrity-before-installing-on-desktop/13472)

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
https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1853769
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 installation)?)

Cheers,


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Re: Defaulting to verify the image integrity before installing on desktop?

Colin Law
On Mon, 25 Nov 2019 at 16:52, Sebastien Bacher <[hidden email]> wrote:
>
> 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 installation)?)

If this is implemented I would vote for the ability to skip the test.
Personally I often burn a stick then check it and then may install to
more than one machine, so it would be a pain to have to repeat the
test on every install.  I think it would be very unusual for a stick
to become corrupted after burning I think.

Colin Law

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Re: Defaulting to verify the image integrity before installing on desktop?

James Cameron
In reply to this post by Sebastien Bacher
It would be better if the cause of the problem was displayed, then the
user could do something about it.  I know this may have to cross
several boundaries of responsibility within the kernel, but magic is
needed.  Media verification is temptingly easy.

A way to turn the feature off would be welcome.  As a derivative that
uses installation media with additional packages added, the extra time
for my users may give me push back.

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Re: Defaulting to verify the image integrity before installing on desktop?

Iain Lane-6
In reply to this post by Sebastien Bacher
On Mon, Nov 25, 2019 at 05:52:21PM +0100, Sebastien Bacher wrote:
> 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
> installation)?)

Sounds like a good idea to me, which will help some people who are faced
with confusing errors otherwise. I would say we want to both allow the
check to be cancelled while it's in progress (e.g. by pressing Escape),
and provide a menu option to boot without checking. For info, Fedora
does both of those things.

Cheers,

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Re: Defaulting to verify the image integrity before installing on desktop?

Mark Rogers
In reply to this post by Sebastien Bacher
On Mon, 25 Nov 2019 at 16:53, Sebastien Bacher <[hidden email]> wrote:

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 installation)?)


On machines with adequate RAM (which is likely most physical machines now?) can the install image be loaded into RAM and verified, with the subsequent install taking place from the RAM copy? Or otherwise cached so that the bulk of the time spent checking the image is saved during the install?

Can any of this be done in a background task while install decisions are made?

Otherwise, changing the default to the safest option makes sense to me, but keeping the faster/riskier version as an option is essential. By all means add a clear disclaimer to the second option too.

But separately: "SQUASHFS error: zlib decompression failed, data probably corrupt" is the kind of error that needs visibility outside a log file, whether or not the install image is checked first. If that's too difficult to fix then image checking is a decent workaround, but in my view it is really only a workaround.

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Re: Defaulting to verify the image integrity before installing on desktop?

Steve Langasek-6
In reply to this post by Iain Lane-6
On Tue, Nov 26, 2019 at 11:02:07AM +0000, Iain Lane wrote:
> On Mon, Nov 25, 2019 at 05:52:21PM +0100, Sebastien Bacher wrote:
> > 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
> > installation)?)

> Sounds like a good idea to me, which will help some people who are faced
> with confusing errors otherwise. I would say we want to both allow the
> check to be cancelled while it's in progress (e.g. by pressing Escape),
> and provide a menu option to boot without checking. For info, Fedora
> does both of those things.

Has anyone measured how much time it takes to run these tests on boot, so we
understand what the cost is to our users of doing this by default?

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Re: Defaulting to verify the image integrity before installing on desktop?

Junien Fridrick
On Tue, Nov 26, 2019 at 09:27:33AM -0800, Steve Langasek wrote:

> On Tue, Nov 26, 2019 at 11:02:07AM +0000, Iain Lane wrote:
> > On Mon, Nov 25, 2019 at 05:52:21PM +0100, Sebastien Bacher wrote:
> > > 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
> > > installation)?)
>
> > Sounds like a good idea to me, which will help some people who are faced
> > with confusing errors otherwise. I would say we want to both allow the
> > check to be cancelled while it's in progress (e.g. by pressing Escape),
> > and provide a menu option to boot without checking. For info, Fedora
> > does both of those things.
>
> Has anyone measured how much time it takes to run these tests on boot, so we
> understand what the cost is to our users of doing this by default?

Seb did in the OP :

> 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)

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Re: Defaulting to verify the image integrity before installing on desktop?

Steve Langasek-6
On Wed, Nov 27, 2019 at 07:02:08AM +0100, Junien Fridrick wrote:
> On Tue, Nov 26, 2019 at 09:27:33AM -0800, Steve Langasek wrote:
> > On Tue, Nov 26, 2019 at 11:02:07AM +0000, Iain Lane wrote:
> > > On Mon, Nov 25, 2019 at 05:52:21PM +0100, Sebastien Bacher wrote:
> > > > 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
> > > > installation)?)

> > > Sounds like a good idea to me, which will help some people who are faced
> > > with confusing errors otherwise. I would say we want to both allow the
> > > check to be cancelled while it's in progress (e.g. by pressing Escape),
> > > and provide a menu option to boot without checking. For info, Fedora
> > > does both of those things.

> > Has anyone measured how much time it takes to run these tests on boot, so we
> > understand what the cost is to our users of doing this by default?

> Seb did in the OP :

> > 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)

Thanks.  For 1-3 minutes, I agree it's critical to make it possible to
bypass this before committing to do this by default.

We probably need to plan for how it can be automatically disabled, as well,
so that it doesn't impact iteration of non-interactive testing.

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