Different iso sizes

[Sebastian Vahl]

Hi.

I've got just a small question: I've created three isos from the same
configuration. Each three created iso images have different sizes. The
first one is 672 MB, the second 683 MB and the third 697 MB. There was
nothing I have changed beetwen them.

Is this related to squashfs? And if so: What would be the "best" way to
create the smallest possible iso?

Sebastian

[David Zeuthen]

On Wed, 2007-03-14 at 13:34 +0100, Sebastian Vahl wrote:
>  Hi.
>  
>  I've got just a small question: I've created three isos from the same
>  configuration. Each three created iso images have different sizes. The
>  first one is 672 MB, the second 683 MB and the third 697 MB. There was
>  nothing I have changed beetwen them. 
For the record I've seen this too and IIRC Bill did some investigation
of the matter.

>  Is this related to squashfs?  
Not sure.

>  And if so: What would be the "best" way to
>  create the smallest possible iso? 
Trial and error right now :-)

     David

[Bill Nottingham]

David Zeuthen (davidz(a)redhat.com) said: 
>  > I've got just a small question: I've created three isos
> from the same
>  > configuration. Each three created iso images have different sizes. The
>  > first one is 672 MB, the second 683 MB and the third 697 MB. There was
>  > nothing I have changed beetwen them.
>  
>  For the record I've seen this too and IIRC Bill did some investigation
>  of the matter. 
I looked briefly. Didn't actually get anywhere with results.

Bill

[Sebastian Vahl]

Am Wed, 14 Mar 2007 12:21:23 -0400
schrieb David Zeuthen <davidz(a)redhat.com&gt;:

>  On Wed, 2007-03-14 at 13:34 +0100, Sebastian Vahl wrote:
>  > Hi.
>  > 
>  > I've got just a small question: I've created three isos from the
>  > same configuration. Each three created iso images have different
>  > sizes. The first one is 672 MB, the second 683 MB and the third 697
>  > MB. There was nothing I have changed beetwen them.
>  
>  For the record I've seen this too and IIRC Bill did some investigation
>  of the matter. 
I'm not alone. :)

>  
>  > Is this related to squashfs? 
>  
>  Not sure. 
Mhh. maybe.

# du -x livecd-20070314-16*
148216  livecd-20070314-1634.iso    (-> mounted as iso1)
150460  livecd-20070314-1647.iso    (-> mounted as iso2)

# du -x iso1/squashfs.img iso2/squashfs.img 
142648  iso1/squashfs.img
144892  iso2/squashfs.img

# du -x iso1/sysroot/os.img iso2/sysroot/os.img 
3145729 iso1/sysroot/os.img
3145729 iso2/sysroot/os.img

# du -xs iso1/sysroot/sysroot iso2/sysroot/sysroot
371260  iso1/sysroot/sysroot
371248  iso2/sysroot/sysroot


>  
>  > And if so: What would be the "best" way to
>  > create the smallest possible iso?
>  
>  Trial and error right now :-) 
Ok. :)

Sebastian

[Jane Dogalt]

--- Sebastian Vahl <ml(a)deadbabylon.de&gt; wrote:

>  Hi.
>  
>  I've got just a small question: I've created three isos from the same
>  configuration. Each three created iso images have different sizes. 
...
>  Is this related to squashfs? And if so: What would be the
> "best" way
>  to
>  create the smallest possible iso? 
This is just a theory, but...

with the livecd generator I'm developing, which at the moment uses the
same basic mechanism as LFS/pilgrim, I actually go ahead and do an
extra full copy of the target system into a fresh ext3 sparse image
file 'container' _after_ the install has completed.

While I haven't done any experiments to verify that my logic is valid,
the theory I was operating under was that with the way the sparse file
works, if you write files to that filesystem and then delete them, you
are going to suffer that disk usage in the sparse ext3 image file even
though the actual file has been 'deleted'.

By waiting until the installation is complete, and then doing _nothing_
but a big tarcopy of the target installed system into a new virgin
sparse filesystem image, then no space would be lost.

If I ever get any actual data to substantiate this theory, I'll post my
test results.

Or maybe livecd-creator already effectively does this.  It's been
awhile since I've looked at those bits of code.

-dmc/jdog



 
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