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This article will explain in detail how the time synchronization configuration of Oracle 11G RAC ntp is. The content of the article is of high quality, so the editor shares it for you as a reference. I hope you will have some understanding of the relevant knowledge after reading this article.

Oracle uses SCN to record transaction operations, and SCN is a timestamp. Design: if there is a difference in the interval time in RAC, the data may be inconsistent. Therefore, if there is an inconsistency in time, it will lead to a cluster restructuring (let a node be restarted). A large time jump will also cause the cluster to start and fencing. Therefore, it is necessary to synchronize RAC time.

Time synchronization method:

1.CTSS (Cluster Time Synchronization Server Daemon)

11G GRID self-provided time synchronization service

If the NTP service has been deployed on all nodes, the CTSS will be operated as Observer mode. In this mode, CTSS will only record time inconsistencies in the cluster alert.log, but will not process them.

If NTP,CTSS is not deployed on all nodes to Active mode the line, and synchronize with the main node. Divided into several ways:

1 > join the cluster at the right time. If there is a time difference at this point, but the difference is within the limit, it will be synchronized step by step, with a small adjustment each time. If the time difference exceeds the limit range, you are not allowed to join the cluster and record it in alert.log.

2 > during the operation process, if the time difference between the node and the master node occurs, the OS time will be accelerated or slowed down to the same time as clock slewing.

CTSS mode View:

# su-grid

$crsctl check ctss

Open the Active mode method:

# service ntpd stop

# chkconfig ntpd off

# mv / etc/ntp.conf / etc/ntp.conf.bak

# su-grid

$crsctl check ctss

Note:

1.CTSS does not shift the system time forward. There are moments in Oracle 10.2 RAC that restart BUG due to the forward time of the start.

2.CTSS can guarantee individual clock time synchronization, but it cannot be consistent with external standard time (Beijing time or Taipei time).

2.Linux NTP (Network Time Protocol)-push

This method ensures both time synchronization and standard time synchronization, and modifies all RAC nodes:

/ etc/ntp.conf, 10.191.130.130pm 10.191.131.131 is a time synchronization server within the company (synchronized with preparation time)

# vi / etc/ntp.conf

Server 10.191.130.130 prefer

Server 10.191.131.131

Driftfile / var/lib/ntp/drift

Broadcastdelay 0.008

# vi / etc/sysconfig/ntpd

# Drop root to id 'ntp:ntp' by default.

OPTIONS= "- x-u ntp:ntp-p / var/run/ntpd.pid-g"

Note: the-x parameter represents the use of clock slewing import mode synchronization to avoid cluster restructuring caused by large time jumps.

Open the ntpd service

# service ntpd start

Turn on ntpd boot start

# chkconfig ntpd on

Check the time synchronization status in a moment:

# ntpstat

Synchronised to NTP server (10.191.130.130) at stratum 4

Time correct to within 529 ms

Polling server every 1024 s

# ntpq-p

Remote refid st t when poll reach delay offset jitter

=

* 10.191.130.130 10.191.131.173 3u 977 1024 23.995-66.546 24.713

+ 10.191.131.131 118.163.81.61 3 u 985 1024 28.876 56.586 10.010

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