The equivalent failure with PostgreSQL would be to update kernel.shmmax with a call to sysctl, and then forget to update /etc/sysctl.conf. Then if the machine reboots PostgreSQL will fail to start because it can't allocate enough memory. It mostly wasn't a redis problem as far as I can tell. That said, Twilio is probably at a big enough scale where they can afford to hire a couple full-time admins to deal with PostgreSQL.