Knoppix Customization Image Size Increase

I have seen several references to the increase in Knoppix image size. I have looked at the effects of this with the 3.2-7-24-EN version and I want to understand why this happens. Here are the statistics:

[OUTLINE]
I pull the contents of the CDROM to harddisk
I pull the contents of the compressed loopback FS to harddisk
I do NOTHING ... add nothing, change nothing
Rebuild the cloop fs
Rebuild the final ISO

Here is a comparison:

Originial ISO
KNOPPIX_V3.2-2003-07-24-EN.iso -> 726171648 (ls)

After CD Boot the 7-24-EN Knoppix 3.2 sizes are:
/KNOPPIX -> 1837388k (du -s)
/cdrom -> 708743k (du -s)
/cdrom/KNOPPIX/KNOPPIX -> 717986603 (ls)

After copying contents to ext3 partition
cdrom/KNOPPIX/KNOPPIX -> 717986603 (du -s)
KNOPPIX.d/ -> 2125956k (du -s)

After Remaking the KNOPPIX File using command:
mkisofs -R -U -V \"KNOPPIX filesystem\" -hide-rr-moved -cache-inodes -no-bak -pad \
KNOPPIX.d/ | create_compressed_fs - 65536 > cdrom/KNOPPIX/KNOPPIX

I get a cloop fs image:
cdrom/KNOPPIX/KNOPPIX -> 740361704 (ls)
Final ISO using :
mkisofs -pad -l -r -v -J -V "KNOPPIX" -hide-rr-moved -o myknoppix.iso -b KNOPPIX/boot.img -c KNOPPIX/boot.cat cdrom

myknoppix.iso -> 748546048 (ls)

The trouble step is clearly the creation of the CLOOP ISO. Some threads have said that it depends on hardware (lots of things, drive RPM, processor, etc). But I don't understand why this would be the case. Slower hardware should just take longer ... not result in a different file size. Am I making a mistake somewhere?

So somehow going through the process without adding anything I gain about 22000000B

Its a mystery to me.
Austin

diffrent cloop version maybe?

The additional information I have:

I have two compressed loopback ISO 9660 Filesystems. The oringal one from the 3.2-7-24-EN version of Knoppix (ORIGINAL) and the one I made directly from that without changing anything, simply copying to ext3 partition, then creating new cloop image (MINE). Here are their stats:

ORIGINAL
ISO Size: 701159 k
du -s in / of mounted cloop fs: 1837388 k
du -s of source the cloop fs was made from: 2125956 k

MINE
ISO Size: 722819 k
du -s in / of mounted cloop fs: 1837390 k
du -s of source the cloop fs was made from: 2125956 k

So I think it is important to note the following things ... the sizes of the mounted loopback filesystems are only different by two bytes BUT the cloop ISO file itself is different by 20000 k. That is 2 kB -> 20000 kB.

OK, so I have come up with a good explaination for this I think. Since cloop compresses its data in 65k blocks (something like that) how you sort the files when you build your compressed loopback filesystem will have a major effect on the final cumulative compression ratio achieved. So you could be splitting your FS into 65k blocks such that you get a BAD compression ratio or you can be splitting it up to compress most efficiently. Since I do not sort my files in any particular manner I just get whatever comes up.

So I will try sorting the same exact file system and build off of that and see if the resuling cloop fs image is different.

Austin

PS - BTW, the cloop versions are identical.

For those that are curious, the size of the KNOPPIX file is different if you sort it, like I suggested. However the difference is miniscule.

Another good tip, you can run "isoinfo -d -i /dev/cloop" after you have inserted your cloop module on the cloop image of your choice. This allows you to look at ISO info that is otherwise not visible.

Granted I still haven't solved my problem.

Austin

Finally a resolution to this issue:

On Mon, Sep 29, 2003 at 08:26:05PM +0200, Baeckeroot alain wrote:

>> Hello
>>
>> I'm running Knoppix-3.3_2003.09.24 and I'm remastering...
>> As I was in trouble, I tried to remaster the same CD whithout changing anything
>> but just test the whole process:
>>
>> I mount (cloop) the huge compressed KNOPPIX/KNOPPIX file
>> I copy it to mydir (for a future chroot apt-get ....)
>> I change nothing, and I
>> mkisofs | create_compress_fs > myKNOPPIX
>>
>> The file is now 715 MB instead of 700 !!! so it doesn't fit into my CD !!!
>>
>> What's wrong ?
>> Are there any options ?
>> I'm working on ext3 filesystem, should I do it on xfs ?


No, you are just victim of a kernel bug in the iso9660 filesystem.
Hardlinks are not correctly copied as hardlinks, so they are split into
individual files and therefore require more space on the destination
filesystem. If you replace all files that are >= 1 Byte and identical by
content to each other, with hardlinks, the allocated space should shrink
accordingly.

Regards
-Klaus Knopper
-----------------------------------

-Austin

Here is a program that will search for duplicate files and then link them:

<a href=http://www.stearns.org/freedups/>http://www.stearns.org/freedups/</a>

It will probably reduce the size of your image by about 30-60 MB.

I got a 33 MB reduction on the 3.3 9-24 disk

Austin