[gentoo-user] Compare two Gentoo machines - please help

[gentoo-user] Compare two Gentoo machines - please help

[Helmut Jarausch]

Hi,

I have two (nearly) identical machines, both running ~amd64 Gentoo up-
to-date and with a (nearly) identical set of installed packages.

Still, on one of these machines KDE crashes with that infamous polkit-
kde-authentication-agent-1 segmentation fault.

On the other machine there is no problem.

How can one smartly compare two Gentoo installations.

Currently I would have to produce an md5sum of all files in 
/etc /usr /var and / and compare these. But there are dozens of 
thousands of files in these directories.

Many thanks for any ideas,
Helmut.

Re: [gentoo-user] Compare two Gentoo machines - please help

[Paul Hartman]

On Tue, May 17, 2011 at 8:42 AM, Helmut Jarausch
<jarausch@igpm.rwth-aachen.de> wrote:
> Hi,
>
> I have two (nearly) identical machines, both running ~amd64 Gentoo up-
> to-date and with a (nearly) identical set of installed packages.
>
> Still, on one of these machines KDE crashes with that infamous polkit-
> kde-authentication-agent-1 segmentation fault.
>
> On the other machine there is no problem.
>
> How can one smartly compare two Gentoo installations.
>
> Currently I would have to produce an md5sum of all files in
> /etc /usr /var and / and compare these. But there are dozens of
> thousands of files in these directories.

You could use rsync with –dry-run to tell you what's different
(without actually transferring any files), or you could perhaps use
diff over ssh to compare a whole tree at once.

Re: [gentoo-user] Compare two Gentoo machines - please help

[Alan Mackenzie]

Good day, Helmut!

On Tue, May 17, 2011 at 03:42:35PM +0200, Helmut Jarausch wrote:
> Hi,

> I have two (nearly) identical machines, both running ~amd64 Gentoo up-
> to-date and with a (nearly) identical set of installed packages.

"Nearly identical" is a bit like "slightly pregnant".  How about making
the two boxes' packages identical (with the same use flags) and seeing if
the problem goes away.

> Still, on one of these machines KDE crashes with that infamous polkit-
> kde-authentication-agent-1 segmentation fault.

> On the other machine there is no problem.

> How can one smartly compare two Gentoo installations.

> Currently I would have to produce an md5sum of all files in 
> /etc /usr /var and / and compare these. But there are dozens of 
> thousands of files in these directories.

Compare the /var/lib/portage/world's just to be sure.  But you've done
that already.  How about a deep comparison of the etc's.

> Many thanks for any ideas,
> Helmut.

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: [gentoo-user] Compare two Gentoo machines - please help

[Volker Armin Hemmann]

On Tuesday 17 May 2011 15:42:35 Helmut Jarausch wrote:
> Hi,
> 
> I have two (nearly) identical machines, both running ~amd64 Gentoo up-
> to-date and with a (nearly) identical set of installed packages.
> 
> Still, on one of these machines KDE crashes with that infamous polkit-
> kde-authentication-agent-1 segmentation fault.
> 
> On the other machine there is no problem.
> 
> How can one smartly compare two Gentoo installations.
> 
> Currently I would have to produce an md5sum of all files in
> /etc /usr /var and / and compare these. But there are dozens of
> thousands of files in these directories.
> 

won't work. Even if the binaries in /usr are compiled with the same settings, 
just the different times of creation will result in different md5sums.

What you want to do is: find the bug. 

Re: [gentoo-user] Compare two Gentoo machines - please help

[Blakawk]

 On Tue, 17 May 2011 17:52:32 +0200, Volker Armin Hemmann wrote:
> On Tuesday 17 May 2011 15:42:35 Helmut Jarausch wrote:
>> Hi,
>>
>> I have two (nearly) identical machines, both running ~amd64 Gentoo 
>> up-
>> to-date and with a (nearly) identical set of installed packages.
>>
>> Still, on one of these machines KDE crashes with that infamous 
>> polkit-
>> kde-authentication-agent-1 segmentation fault.
>>
>> On the other machine there is no problem.
>>
>> How can one smartly compare two Gentoo installations.
>>
>> Currently I would have to produce an md5sum of all files in
>> /etc /usr /var and / and compare these. But there are dozens of
>> thousands of files in these directories.
>>
>
> won't work. Even if the binaries in /usr are compiled with the same
> settings,
> just the different times of creation will result in different 
> md5sums.
>
> What you want to do is: find the bug.

 As far as i remember, i don't see why modification times will enter in 
 the md5sum computation process, as they are not part of the file but of 
 the filesystem's inode... it's definitely possible to compare two 
 binaries on two different system if they are compiled with the same 
 compiler version and libraries !

-- 
 Blog: http://gentooist.com
 Twitter: http://twitter.com/blakawk

[gentoo-user] Re: Compare two Gentoo machines - please help

[James]

Helmut Jarausch <jarausch <at> igpm.rwth-aachen.de> writes:


> I have two (nearly) identical machines, both running ~amd64 Gentoo up-
> to-date and with a (nearly) identical set of installed packages.

> How can one smartly compare two Gentoo installations.

Tricky problem. Maybe set up the good machine
to build packages from and sync the second (troublesome)
machine off of the good machine ?


Just a thought.

hth,
James

Re: [gentoo-user] Compare two Gentoo machines - please help

[Leonardo Guilherme]

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Leonardo


2011/5/17 Paul Hartman <paul.hartman+gentoo@gmail.com>

> On Tue, May 17, 2011 at 8:42 AM, Helmut Jarausch
> <jarausch@igpm.rwth-aachen.de> wrote:
> > Hi,
> >
> > I have two (nearly) identical machines, both running ~amd64 Gentoo up-
> > to-date and with a (nearly) identical set of installed packages.
> >
> > Still, on one of these machines KDE crashes with that infamous polkit-
> > kde-authentication-agent-1 segmentation fault.
> >
> > On the other machine there is no problem.
> >
> > How can one smartly compare two Gentoo installations.
> >
> > Currently I would have to produce an md5sum of all files in
> > /etc /usr /var and / and compare these. But there are dozens of
> > thousands of files in these directories.
>
> You could use rsync with –dry-run to tell you what's different
> (without actually transferring any files), or you could perhaps use
> diff over ssh to compare a whole tree at once.
>
>
I would go with Paul's rsync solution.

Leonardo

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Re: [gentoo-user] Compare two Gentoo machines - please help

[Stroller]

On 17/5/2011, at 4:52pm, Volker Armin Hemmann wrote:
> ...
> What you want to do is: find the bug. 

Or, y'know: just `emerge -e world` and see if it goes away. 

I know this is a bit of brute force & ignorance, but:

1) if the bug goes away when you recompile everything then it was a difficult bug to reproduce, anyway (at least relatively speaking) and it's not clear how many other people you'll help by understanding and reporting such a "transient" issue.

2) if the bug persists after recompiling everything then you know that it's possible to reproduce it, there's a higher possibility that the bug will affect other people, and you can usefully report it upstream, once you pin it down.

Stroller.

Re: [gentoo-user] Compare two Gentoo machines - please help

[Volker Armin Hemmann]

On Tuesday 17 May 2011 17:57:42 Blakawk wrote:

>  As far as i remember, i don't see why modification times will enter in
>  the md5sum computation process, as they are not part of the file but of
>  the filesystem's inode... it's definitely possible to compare two
>  binaries on two different system if they are compiled with the same
>  compiler version and libraries 

in theory. In practice only a slight change here and there - might result in 
huge changes. 'Almost identical' but the things that are not identical will 
screw you up. Almost identical is like 'totally different' in this case.

Instead wasting time comparing the machines, he should find the culprit for 
the segfault. KDE's backtracking tool (drkonqi) and strace help a lot with 
that. If he knows where it fails, he at least has a chance to find out why.

Re: [gentoo-user] Compare two Gentoo machines - please help

[Helmut Jarausch]

Thanks to all of you who have tried to help me.

As it turned out, comparing MD5 sum is intractable,
/usr/lib64 alone contained more than 500,000 files !

The /etc tree didn't show significant differences.

So, I resorted to keep my 4 cores busy over the weekend to
re-emerge the whole machine.

That's the price for a highly configurable and up-to-date system like 
Gentoo - but I like it. But it's the first time I needed to do it since
several years, now.

Helmut.

On 05/17/2011 10:21:16 PM, Volker Armin Hemmann wrote:
> On Tuesday 17 May 2011 17:57:42 Blakawk wrote:
> 
> >  As far as i remember, i don't see why modification times will 
> enter
> in
> >  the md5sum computation process, as they are not part of the file
> but of
> >  the filesystem's inode... it's definitely possible to compare two
> >  binaries on two different system if they are compiled with the 
> same
> >  compiler version and libraries 
> 
> in theory. In practice only a slight change here and there - might
> result in 
> huge changes. 'Almost identical' but the things that are not 
> identical
> will 
> screw you up. Almost identical is like 'totally different' in this
> case.
> 
> Instead wasting time comparing the machines, he should find the
> culprit for 
> the segfault. KDE's backtracking tool (drkonqi) and strace help a lot
> with 
> that. If he knows where it fails, he at least has a chance to find 
> out
> why.
> 
> 
> 
>