Re: [debian-knoppix] remastering: problems with create_compressed_fs
Actually i did exactly the same but with mounting with cloop and guess what? my file had 733....bytes ...? ok so we agree there is some overhead? but how can i get rid of it? ;)
smaller block size?
good night
Simon
--
On Mon, 30 Jun 2003 15:38:39 -0700
Jared Rhine <jared@wordzoo.com> wrote:
> [Klaus == knopper@linuxtag.org on Sun, 29 Jun 2003 23:09:03 +0200]
>
> >> i decompressed the KNOPPIX cloop fs and compressed it again ...and
> >> it had grown about 10mb
>
> Klaus> Watch out for hardlinks! This could be the reason.
>
> It could also be that compression is not perfectly symmetric; that
> uncompressing and recompressing again produces a slightly larger file.
> There's some evidence for this, shown below. Doing an uncompress
> followed immediately by a compress expands the KNOPPIX file from
> 725,032,363 bytes to 727,812,929 bytes. This probably doesn't happen
> when mounting using cloop loopback.
>
> -- begin --
>
> -> cd /mnt/d4/test
>
> -> ls -l
> total 716836
> -rw-r--r-- 1 jared jared 733317120 Jun 30 03:48 knoppix_v3.2-2003-06-06-en.iso
>
> -> sudo mount -t iso9660 -o loop knoppix_v3.2-2003-06-06-en.iso /mnt/test
>
> -> ls -l /mnt/test/KNOPPIX/KNOPPIX
> -r--r--r-- 1 root root 725032363 Jun 6 09:06 /mnt/test/KNOPPIX/KNOPPIX
>
> -> extract_compressed_fs /mnt/test/KNOPPIX/KNOPPIX > /mnt/d4/test/extracted
> 29239 blocks of size 65536. Preamble:
> #!/bin/sh
> insmod cloop.o file=$0 && mount -r -t iso9660 /dev/cloop $1
> exit $?
>
> Block 0 length 11945 => 65536
> Block 1 length 30324 => 65536
> Block 2 length 30546 => 65536
> Block 3 length 29327 => 65536
> Block head:78DAECBD877F1CD5
> Block tail:61CF0E315D18D948
> Block 4 length 34020 => 65536
> Block 5 length 18788 => 65536
> Block 6 length 9368 => 65536
> [...]
>
> -> ls -l .
> total 2589964
> -rw-r--r-- 1 jared jared 1916207104 Jun 30 04:13 extracted
> -rw-r--r-- 1 jared jared 733317120 Jun 30 03:48 knoppix_v3.2-2003-06-06-en.iso
>
> -> cat extracted | create_compressed_fs - 65536 > recompressed
> Block# 0 size 65536 -> 11963 [compression ratio 18%, overall: 18%]
> Block# 1 size 65536 -> 30321 [compression ratio 46%, overall: 32%]
> Block# 2 size 65536 -> 30545 [compression ratio 46%, overall: 37%]
> [...]
>
> -> ls -l /mnt/test/KNOPPIX/KNOPPIX /mnt/d4/test
> -r--r--r-- 1 root root 725032363 Jun 6 09:06 /mnt/test/KNOPPIX/KNOPPIX
>
> /mnt/d4/test:
> total 3301420
> -rw-r--r-- 1 jared jared 1916207104 Jun 30 04:13 extracted
> -rw-r--r-- 1 jared jared 733317120 Jun 30 03:48 knoppix_v3.2-2003-06-06-en.iso
> -rw-r--r-- 1 jared jared 727812929 Jun 30 05:29 recompressed
>
> -- end --
>
> -- jared@wordzoo.com
>
> "A black hole is where God is dividing by zero."
> -- attributed to Roger Smith
> _______________________________________________
> debian-knoppix mailing list
> debian-knoppix@linuxtag.org
> http://mailman.linuxtag.org/mailman/listinfo/debian-knoppix
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