PRVG-13606
Saw PRVG-13606 when I verify the RAC environment by runcluvfy.sh before actually installing grid infrastructure.
[grid@primary01 ~]$ cd $ORACLE_HOME
[grid@primary01 grid]$ ./runcluvfy.sh stage -pre crsinst -n primary01,primary02 -verbose
...
Verifying Network Time Protocol (NTP) ...FAILED
Verifying chrony daemon is synchronized with at least one external time
source ...FAILED
primary01: PRVG-13606 : chrony daemon is not synchronized with any external
time source on node "primary01".
It seems that chronyd is working, but it's not synced with any NTP server.
[root@primary01 ~]# systemctl status chronyd
● chronyd.service - NTP client/server
Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled)
Active: active (running) since Sun 2021-02-14 18:47:58 CST; 16min ago
Docs: man:chronyd(8)
man:chrony.conf(5)
Process: 693 ExecStartPost=/usr/libexec/chrony-helper update-daemon (code=exited, status=0/SUCCESS)
Process: 667 ExecStart=/usr/sbin/chronyd $OPTIONS (code=exited, status=0/SUCCESS)
Main PID: 686 (chronyd)
CGroup: /system.slice/chronyd.service
└─686 /usr/sbin/chronyd
Feb 14 18:47:58 primary01.example.com systemd[1]: Starting NTP client/server...
Feb 14 18:47:58 primary01.example.com chronyd[686]: chronyd version 3.2 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER +...DEBUG)
Feb 14 18:47:58 primary01.example.com chronyd[686]: Frequency 0.000 +/- 1000000.000 ppm read from /var/lib/chrony/drift
Feb 14 18:47:58 primary01.example.com systemd[1]: Started NTP client/server.
Hint: Some lines were ellipsized, use -l to show in full.
There's also nothing particular from the status. So we check the configuration of chronyd.
[root@primary01 ~]# vi /etc/chrony.conf
...
server 0.ol.pool.ntp.org iburst
server 1.ol.pool.ntp.org iburst
server 2.ol.pool.ntp.org iburst
server 3.ol.pool.ntp.org iburst
Let's check whether we can connect to NTP servers or not.
[root@primary01 ~]# nslookup 0.ol.pool.ntp.org
Server: 192.168.0.199
Address: 192.168.0.199#53
** server can't find 0.ol.pool.ntp.org: NXDOMAIN
[root@primary01 ~]# nslookup 1.ol.pool.ntp.org
Server: 192.168.0.199
Address: 192.168.0.199#53
** server can't find 1.ol.pool.ntp.org: NXDOMAIN
[root@primary01 ~]# nslookup 2.ol.pool.ntp.org
Server: 192.168.0.199
Address: 192.168.0.199#53
** server can't find 2.ol.pool.ntp.org: NXDOMAIN
[root@primary01 ~]# nslookup 3.ol.pool.ntp.org
Server: 192.168.0.199
Address: 192.168.0.199#53
** server can't find 3.ol.pool.ntp.org: NXDOMAIN
No, we can't reach them.
That is to say, PRVG-13606 means that NTP service is running in your database server, however, the NTP servers are unreachable. Mostly, it's a network problem.
Solution
The root cause of network unreachability can be any types, such as lease line, antivirus, router, firewall or NTP server itself.
In this case, we should replace those time servers with available ones to solve PRVG-13606. For example, *.jp.pool.ntp.org are working time servers. You can use NTP servers near your location.
[root@primary01 ~]# nslookup 0.jp.pool.ntp.org
Server: 192.168.0.199
Address: 192.168.0.199#53
Non-authoritative answer:
Name: 0.jp.pool.ntp.org
Address: 172.104.118.14
Name: 0.jp.pool.ntp.org
Address: 157.7.153.56
Name: 0.jp.pool.ntp.org
Address: 3.114.30.212
Name: 0.jp.pool.ntp.org
Address: 103.202.216.35
We modify the configuration file of chronyd as below.
[root@primary01 ~]# vi /etc/chrony.conf
...
server 0.jp.pool.ntp.org iburst
server 1.jp.pool.ntp.org iburst
server 2.jp.pool.ntp.org iburst
server 3.jp.pool.ntp.org iburst
Don't forget to restart chronyd daemon.
[root@primary01 ~]# systemctl restart chronyd
There's a successful installation of grid infrastructure 19c can be found in this website.