> Is it normal that when using the "tar" command to create a big archive, > the whole machine becomes unresponsive, e.g. several dozens of seconds > to do some operation (e.g. starting an xterm, or making Firefox react)? > > htop shows that there is still plenty of memory and atop shows nothing > special, except 100% disk busy of course. > Yes. You may want to change the "nice" level of the tar command so that it doesn't take up so much disk time.