[Ubuntu] system boot problem

부팅 중 다음과 같은 메시지가 나오며 부팅 실패 

Gave up waiting for root device. Common problems:

- Boot args (cat /proc/cmdline)

  - Check rootdelay= (did the system wait long enough?)

  - Check root= (did the system wait for the right device)

- Missing modules (cat /proc/modules; ls /dev)

ALERT! /dev/disk/by-uuid/96889309-5f73-4688-8354-e64cd1bb158f does not exist. Dropping to a shell!

우선 exit로 부팅을 진행한다.