iotop -C 5 12 # or iotop

fs_usage

top -o cpu

iosnoop

execsnoop -v

dtruss -n firefox-bin

fs_usage -w -f filesys -e grep | grep -i ' write '

http://dtrace.org/blogs/brendan/2011/10/10/top-10-dtrace-scripts-for-mac-os-x/