Squashfs-ed knoppix

[Forester]

I recommend this !

I remastered the DVD edition of 6.4.3 (with a few location modifications). It's big.

The cloop compressed file system was made with the -b 'try all and keep the best" option.
The cloop method requires either 9 Gb of virtual memory I don't have or a 9 Gb temporary file.

First the size of the KNOPPIX file produced:

cloop:      3.85 Gb
squashfs:   3.76 Gb

Second the time taken:

cloop:      94 minutes
squashfs:    9 minutes

Third temporary disk space required:

cloop:      19 Gb
squashfs:   10 Gb

That's what they call a Grand Slam.

And for me there's a bonus. Boot time on my laptop is about 60 s with either solution. Take my USB stick into work where the whacky set up I have with the Virtual Machine makes for a very slow boot ...

Boot time at work:

cloop:      ~ 4 minutes
squashfs:   < 2 minutes

The udev probing is a lot quicker with squashfs at work. I've no idea why but it's a very welcome result.

The mksquahfs tool I had to install (from the Debian Squeeze repository) listed zlib1g as a 'depends on' package so I was surprised to see such a difference in size. Fundamentally, how good the compression is depends on the compression library used underneath. lzma is supposed to compress better than bzip2 which is supposed to produce compresed files 20 % smaller than good old zlib (aka gzip). It is also supposed to be fast to decompress. So there are good things to come.

It may be that Knoppix has stuck to cloop for sentimental reasons but it may just have been one less change to worry about at the time Knoppix 6 first came out two years ago. I don't think squashfs was part of the standard kernel then. If cloop reappears with support for lzma I'll be surprised.

As for the outrageous claim that Knoppix requires at least 1 Gb of memory and cloop is to blame ...

... the original article has gone but I found a precis at https://www.experts123.com/q/what-ar...d-knoppix.html and offending text is ....

Finnix can be copied to RAM and run in only 192MB; Knoppix requires at least 1GB

Doh ! Finnix has no X, no desktop, no mega Windoze-style applications with user-friendly OK buttons so of course it is small and can be loaded into a modest amount of memory and, of course, when Finnix compares itself with Knoppix is used the toram cheatcode, which loads the entire uncompressed Knoppix iso into memory and comes out with the obvious statement that Knoppix requires at least 1 Gb of memory. By that same reasoning I need 10 Gb of memory to run by Knoppix DVD but my laptop doesn't have that much memory.

The claim is about as useful as stating that oranges and bananas aren't the same thing because bananas take a lot less time to peel and suddenly all sorts of people are deducing that this is why monkeys are smart and that drinking orange juice is bad for your health.

Now I hope squashfs has come a long way since I first met it. My first Knoppix was 3.6. It ran like a dream but I was a newbie and someone told me to install Ubuntu to hard disk. I couldn't install Breezy from LiveCD. A year later I couldn't Dapper. A year later I couldn't install Feisty until I tried the alternative (aka Debian) installer. All those squashfs error I had had nothing to do with my hardware or my media - it was Ubuntu's user friendly way of telling me I didn't have enough memory.

Perhaps Knoppix has a reason to stick with cloop after all.

[Werner P. Schulz]

The cloop compressed file system was made with the -b 'try all and keep the best" option.
...
Second the time taken:
Code:
cloop: 94 minutes
squashfs: 9 minutes

... building the cloop compressed file system without the "-b" parameter works about twelve times faster. And the effect by using the "-b" parameter isn't worth to waste so much time for only a little better compression.

[kl522]

Perhaps Knoppix has a reason to stick with cloop after all.

You guys are diplomatic !
I think it is strictly sentimental value and perhaps better way of saying is, for backward compatibility.

Each time I wanted to compile cloop, I have to look out for patches for it. Kernel 2.6.35, .36, .37, .38. Every version there is something to tweak. Perhaps the Linux kernel is to blame, and perhaps squashfs kernel source also requires changes, but hey, someone has already modified it for me !

If one checks kernel 2.6.38, it has LZMA2 for SQUASHFS ( aka XZ compresion). This fella claims it compresses better than lzma :-

http://chakra-project.org/bbs/viewtopic.php?id=4145

Cheers.

p/s: I am quite surprised about the time taken difference. Perhaps the mksquashfs was not done with lzma compression. But hey, without lzma it is already smaller than the '-b' of cloop ?

[utu]

I would like to see a comparison of the time it takes to boot
a LiveUSB (better yet, a LiveSDCard) made from a
Knoppix 6.4.x LiveCD, with the only difference being
between cloop and squashfs. Times for both, that is.