bzip2, gzip, or zip. Which will win the race?

= File characteristic = 
quick# ls -alh embedded.img
> -rw-r--r--  1 root  wheel   1.0G Nov  4 16:55 embedded.img

quick# mdconfig -a -t vnode -f embedded.img
> md0
quick# mount /dev/md0
> md0%    md0s1%  md0s1a% 
quick# mount /dev/md0s1a /mnt/
quick# df -h | grep mnt
> /dev/md0s1a    961M    189M    695M    21%    /mnt

= Experiments =

quick# time zip embedded.img.zip embedded.img
>  adding: embedded.img
> 31.350u 0.706s 0:32.23 99.4%	223+1310k 4+604io 0pf+0w
quick# time gzip embedded.img
> 36.136u 0.781s 0:37.13 99.4%	42+1491k 2+604io 0pf+0w
quick# time bzip2 embedded.img
> 91.701u 0.961s 1:32.83 99.8%	37+1496k 1+533io 0pf+0w

quick# ls -lah embedded.img.*
> -rw-r--r--  1 root  wheel    67M Nov  4 16:55 embedded.img.bz2
> -rw-r--r--  1 root  wheel    75M Nov  4 16:55 embedded.img.gz
> -rw-r--r--  1 root  wheel    76M Nov  4 16:58 embedded.img.zip

quick# time unzip embedded.img.zip
> Archive:  embedded.img.zip
>  inflating: embedded.img            
> 8.175u 1.237s 0:18.30 51.3%	145+1354k 0+8000io 0pf+0w
quick# time gunzip embedded.img.gz 
> 6.076u 1.380s 0:17.98 41.4%	42+1500k 0+8000io 0pf+0w
quick# time bunzip2 embedded.img.bz2 
> 20.996u 1.935s 0:31.99 71.6%	37+1487k 0+8000io 0pf+0w


= Results =
Use bzip2 for best compression, but trade off is time (roughly 2x more), still do-able though. Also do mind that zip is the only one support by Windows(r) by default. Others require programs like 7-Zip to be installed. Secondly zip is not installed on the system by default, use:
quick# pkg_add -r zip unzip