Journaling filesystems don't "journal" all the activity in perpetuity. They typically just journal the changes until they're committed to disk, usually for les

Journaling filesystems don't "journal" all the activity in perpetuity. They typically just journal the changes until they're committed to disk, usually for less than a second. See http://www.nobius.org/~dbg/practical-file-system-design.pdf http://www.nobius.org/~dbg/practical-file-system-design.pdf, section 7.2 "How Does Journaling Work?".