Custom ISO 4x bigger than the original?

littlebigman · 09-10-2010, 05:44 AM

Hello,

This is my first attempt at upgrading a live ISO file. Things seem to have worked OK, but the resulting ISO is four times bigger than the original:

original.iso : 334.917.632 bytes
ubuntu-2.6.31-22-custom.iso : 1.590.505.472

I followed the LiveCDCustomization HOWTO:
1. In home directory, mount ISO to explode squashfs in ~/edit, and the rest of the ISO into ~/extract-cd
2. chroot to ~/edit (ie. exploded squashfs), upgrade kernel + applications, and build new initr.gz
3. exit chroot, and rebuild ISO

Does someone know why the ISO ends up being so much bigger?

Thank you.

linus72 · 09-10-2010, 06:15 AM

thats kinda weird

did you remove the old kernel(s) images,headers?
you went exactly by that how-to?
which ubuntu is that? 10.04?
what was the original iso?

jefro · 09-10-2010, 04:24 PM

Maybe you didn't delete old data and compress the new data in the fuse (or other filesystem)?

littlebigman · 09-11-2010, 05:10 AM

Thanks guys for the help. It's a rescue disk based on Xubuntu 9.10.

In the Customizations section, I left everything as-is, and simply...
- removed the NV driver and added the Nouveau driver so that X would work OK with an Nvidia chip
- using "apt-get ugprade", upgraded the kernel + initrd.gz to the latest available, and copied vmlinuz/initrd.gz into ~/extract-cd (since the squashfs doesn't contain the kernel, which is found at the root of the ISO file)

I ran "sudo mksquashfs edit extract-cd/casper/filesystem.squashfs -no-duplicates" without the "-nolzma" because the HOWTO says: "The -nolzma option is only available from Hardy , and was removed in Karmic"

I added "-no-duplicates" because otherwise, it would get stuck at 6005 (Google shows that other users have had the same problem.)

The HOWTO doesn't mention "fuse". What does it do?

BTW, does someone know what "mkinitramfs" does precisely? Does it take everything that lives in /lib/modules, and save those into a compressed file?

Thank you.

robertjinx · 09-11-2010, 06:35 AM

mkinitramfs created the initrd.img file need it to boot the kernel, you can find the initrd files in /boot and they gonna look
something like: initrd.img-2.6.32-22-generic (example)

If you do a LiveCD you should use LZMA and make sure that your squashfs module from your kernel supports LZMA compression.

jefro · 09-11-2010, 03:11 PM

In this case the squash file not fuse.

littlebigman · 09-12-2010, 03:04 PM

Thanks for the help. I'll investigate further to find why the output ISO is so much bigger than the original.

littlebigman · 09-12-2010, 04:21 PM

Quote:

Originally Posted by robertjinx

If you do a LiveCD you should use LZMA and make sure that your squashfs module from your kernel supports LZMA compression.

Thanks for the tip. The LiveCDCustomization says no to use "-nolzma" in 9.10 and later, and the filesystem.squashfs output is about 300MB.

So if I get a 1.5GB ISO, it looks like it has something to do with mkisofs:

Code:

sudo mkisofs -D -r -V "$IMAGE_NAME" -cache-inodes -J -l -b extract-cd/isolinux/isolinux.bin -c extract-cd/isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -o ../ubuntu-2.6.31-22-custom.iso .

[...]
Total translation table size: 2048
Total rockridge attributes bytes: 5228732
Total directory bytes: 17248256
Path table size(bytes): 88556
Max brk space used 2819000
613316 extents written (1197 MB)

$ ll ../ubuntu-2.6.31-22-custom.iso
-rw-r--r-- 1 root root 1256071168 2010-09-12 12:34 ../ubuntu-2.6.31-22-custom.iso

Does someone know why mkisofs ends up building an ISO file that is so much bigger than the original?

Thank you.

robertjinx · 09-13-2010, 04:07 AM

How big is "." or directory which you are building before you create the iso?

littlebigman · 09-20-2010, 03:13 AM

Thanks for the help, and sorry about the delayed response.

Fact is, the directory where the live root filesystem (squashfs) is unpacked does weigh 884MB already even after running the commands specified in the HOWTO above to trim down the fat before building a new ISO:

Code:

$ du -h ./edit
884M    ./edit/

$ du -h ./extract-cd/
17M     ./extract-cd/

$ ls -al ~
~/896.798.720 ubuntu-2.6.31-22-custom.iso

Does someone know how to investigate why I went from the original ISO of 350MB and ended up with a 900MB file after just upgrading its kernel?

Thank you.