
-- Indispensable --
dstat - replacement for vmstat, iostat, mpstat, sar, etc.
blktrace (btrace) - traces all IO activity in the system
strace - traces all system calls a process makes
ltrace - traces all dlyb calls a process makes
filefrag - deterime file fragmentation

pidstat - display process statistics (use -t to show threads)

-- Check out --
rrdtool (and converters like sar2rrd)

