시스템 시간 동기화 (CentOS 8)

chrony 설치 확인

[root@onnada-instance ~]# rpm -qa | grep chrony

chrony-3.5-1.el8.x86_64

GCP에는 이미 설치되어 있다. 없으면 설치

[root@onnada-instance ~]# dnf install chrony

chrony 서비스 확인

[root@onnada-instance ~]# systemctl status chronyd

● chronyd.service - NTP client/server

   Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled)

   Active: active (running) since Sat 2021-01-09 13:57:26 UTC; 3h 11min ago

timezone list 확인

[root@onnada-instance ~]# timedatectl list-timezones

timezone 설정

[root@onnada-instance ~]# timedatectl set-timezone Asia/Seoul

설정 파일에서 구글 주석, 타임존 추가

[root@onnada-instance ~]# vi /etc/chrony.conf

# These servers were defined in the installation:

#server metadata.google.internal iburst

server time.bora.net iburst

server send.mx.cdnetworks.com iburst

server time.google.com iburst

systemd 데몬 등록 및 재시작

[root@onnada-instance ~]# systemctl enable chronyd

[root@onnada-instance ~]# systemctl restart chronyd

시간 동기화 실행

[root@onnada-instance ~]# timedatectl set-ntp true

설정 확인

[root@onnada-instance ~]# timedatectl

               Local time: Sun 2021-01-10 02:51:35 KST

           Universal time: Sat 2021-01-09 17:51:35 UTC

                 RTC time: Sat 2021-01-09 17:51:35

                Time zone: Asia/Seoul (KST, +0900)

System clock synchronized: yes

              NTP service: active

          RTC in local TZ: no

동작 확인

[root@onnada-instance ~]# chronyc sources -v

210 Number of sources = 3

  .-- Source mode  '^' = server, '=' = peer, '#' = local clock.

 / .- Source state '*' = current synced, '+' = combined , '-' = not combined,

| /   '?' = unreachable, 'x' = time may be in error, '~' = time too variable.

||                                                 .- xxxx [ yyyy ] +/- zzzz

||      Reachability register (octal) -.           |  xxxx = adjusted offset,

||      Log2(Polling interval) --.      |          |  yyyy = measured offset,

||                                \     |          |  zzzz = estimated error.

||                                 |    |           \

MS Name/IP address         Stratum Poll Reach LastRx Last sample

===============================================================================

^* metadata.google.internal      2   6    17    63  +7585ns[  +42us] +/-  280us

^- send.mx.cdnetworks.com        2   6    17    63   -332us[ -298us] +/-   26ms

^- time4.google.com              1   6    17    65    -58us[  -24us] +/-   24ms​