Shulou(Shulou.com)06/01 Report--

Cluster Time Synchronization Service (CTSS) can detect time synchronization problems between nodes in a cluster. CTSS is installed as part of Oracle CLusterware. If it detects the existence of a time synchronization service (such as NTP or Chrony) in the system, or if the time synchronization service configuration is valid or broken, then it will run in observe mode. For example, if the / etc/ntp.conf file exists on any node in the cluster, the CTSS will run in watch mode even if the time synchronization service is not running. If CTSS does not detect the existence of time synchronization service or time synchronization service configuration information on any node of the cluster, it will run in active mode and perform time management on the cluster. If CTSS is running in active mode on one node in the cluster, watching mode on another node, and there is no NTP, time synchronization software is running, then you can change CTSS to observe mode by creating a file called / etc/ntp.conf. Changing to observe mode for CTSS will write a message in alert.log. When a node joins a cluster, if CTSS is running in active mode, it will compare the time with those joining nodes using nodes in the cluster that reference clocks. If there is a difference between the two times and the difference is limited by a specific setting, then CTSS will perform time synchronization. Clock nodes in the cluster will not be able to synchronize using the reference clock (the CTSS is used as the base time, and the node it is on is the first node to start in the cluster) for various reasons. When this happens, the CTSS performs slewing time synchronization, which accelerates or slows down the system time on the node until they are synchronized with the referenced system time. In this time synchronization method, CTSS does not adjust the time backward, it ensures that the system time increases one-way.

When Orale cluster software starts, if CTSS runs in active mode and the time difference exceeds the set limit (24 hours), then CTSS will generate an alarm in alert.log and exit, then Oracle cluster software will fail to start. If you have to manually adjust the nodes that join the cluster, CTSS can manage the time for those nodes after starting the Oracle cluster software. When performing slewing time synchronization, CTSS never adjusts the time backwards using the reference clock. CTSS periodically writes alerts to alert.log that include how it uses the reference clock to adjust node time.

CTSS will write alarm information to Oracle cluster alert.log and syslog when the following situations occur:

. Check that the time has changed

. Check that there is a significant time difference compared with the reference clock.

. Switch from observation mode to active mode or from active mode to observation mode

Using CTSS to synchronize time in a cluster can facilitate the diagnosis of Oracle cluster problems because there is no need to consider a series of events that affect time on different nodes.

Activate and disable cluster time synchronization

CTSS can be activated in order to set up a time management service for the cluster. You can disable CTSS if you want to use different cluster time synchronization services. In order to activate CTSS, you must stop the time synchronization service with deleting third parties for all nodes in the cluster. When CTSS is activated, the time management service mode of the cluster is checked.

The following RAC makes the CTSS run in an observational manner because there is third-party time synchronization service configuration information on all nodes

Detect whether there is a third-party time synchronization service in the cluster node

[root@jytest1 ~] # find /-name ntp.conf/etc/ntp.conf [root@jytest2 ~] # find /-name ntp.conf/etc/ntp.conf [grid@jytest1 ~] $cluvfy comp clocksync-n allVerifying Clock Synchronization... CTSS is in Observer state. Switching over to clock synchronization checks using NTP Verifying Network Time Protocol (NTP)... Verifying'/ etc/ntp.conf'... PASSED Verifying'/ etc/chrony.conf'... PASSED Verifying'/ var/run/chronyd.pid'... PASSED Verifying Daemon 'chronyd'... PASSED Verifying NTP daemon or service using UDP port 123... PASSED Verifying chrony daemon is synchronized with at least one external time source... FAILED (PRVG-13606) Verifying Network Time Protocol (NTP)... FAILED (PRVG-1063) Verifying Clock Synchronization... FAILED (PRVG-1063 PRVG-13606) Verification of Clock Synchronization across the cluster nodes was unsuccessful on all the specified nodes.Failures were encountered during execution of CVU verification request "Clock Synchronization across the cluster nodes" .Verifying Clock Synchronization... FAILED Verifying Network Time Protocol (NTP)... FAILED PRVG-1063: configuration files for more than one time synchronization service were found on nodes of the cluster configuration file "/ etc/chrony.conf" was found on nodes "jytest2,jytest1" configuration file "/ etc/ntp.conf" was found on nodes "jytest2 Jytest1 "Verifying chrony daemon is synchronized with at least one external time source... FAILED jytest2: PRVG-13606: chrony daemon is not synchronized with any external time source on node" jytest2 ". Jytest1: PRVG-13606: chrony daemon is not synchronized with any external time source on node "jytest1" .CVU operation performed: Clock Synchronization across the cluster nodesDate: Mar 3, 2018 12:58:07 AMCVU home: / u01/app/product/12.2.0/crs/User: grid [grid@jytest2 ~] $cluvfy comp clocksync-n allVerifying Clock Synchronization... CTSS is in Observer state. Switching over to clock synchronization checks using NTP Verifying Network Time Protocol (NTP)... Verifying'/ etc/ntp.conf'... PASSED Verifying'/ etc/chrony.conf'... PASSED Verifying'/ var/run/chronyd.pid'... PASSED Verifying Daemon 'chronyd'... PASSED Verifying NTP daemon or service using UDP port 123... PASSED Verifying chrony daemon is synchronized with at least one external time source... FAILED (PRVG-13606) Verifying Network Time Protocol (NTP)... FAILED (PRVG-1063) Verifying Clock Synchronization... FAILED (PRVG-1063 PRVG-13606) Verification of Clock Synchronization across the cluster nodes was unsuccessful on all the specified nodes.Failures were encountered during execution of CVU verification request "Clock Synchronization across the cluster nodes" .Verifying Clock Synchronization... FAILED Verifying Network Time Protocol (NTP)... FAILED PRVG-1063: configuration files for more than one time synchronization service were found on nodes of the cluster configuration file "/ etc/chrony.conf" was found on nodes "jytest2,jytest1" configuration file "/ etc/ntp.conf" was found on nodes "jytest2 Jytest1 "Verifying chrony daemon is synchronized with at least one external time source... FAILED jytest2: PRVG-13606: chrony daemon is not synchronized with any external time source on node" jytest2 ". Jytest1: PRVG-13606: chrony daemon is not synchronized with any external time source on node "jytest1" .CVU operation performed: Clock Synchronization across the cluster nodesDate: Mar 3, 2018 1:11:12 AMCVU home: / u01/app/product/12.2.0/crs/User: grid

Use the grid user to execute the crsctl check ctss command to view the running mode of CTSS, and the command results are displayed in observation mode

[grid@jytest1 ~] $crsctl check ctssCRS-4700: The Cluster Time Synchronization Service is in Observer mode. [grid@jytest2 ~] $crsctl check ctssCRS-4700: The Cluster Time Synchronization Service is in Observer mode.

Now delete the third-party time synchronization service from the cluster node

[root@jytest1 ~] # rm-rf / etc/ntp.conf [root@jytest1 ~] # rm-rf / etc/chrony.conf [root@jytest1 ~] # rm-rf / var/run/chronyd.pid [root@jytest2 ~] # rm-rf / etc/ntp.conf [root@jytest2 ~] # rm-rf / etc/chrony.conf [root@jytest2 ~] # rm-rf / var/run/chronyd.pid

Checking the running mode of CTSS again, you can see that CTSS has changed from observation mode to active mode.

[grid@jytest1 ~] $crsctl check ctssCRS-4701: The Cluster Time Synchronization Service is in Active mode.CRS-4702: Offset (in msec): 100 [grid@jytest1 ~] $cluvfy comp clocksync-n allVerifying Clock Synchronization... PASSEDVerification of Clock Synchronization across the cluster nodes was successful.CVU operation performed: Clock Synchronization across the cluster nodesDate: Mar 3 2018 1:14:39 AMCVU home: / u01/app/product/12.2.0/crs/User: grid [grid@jytest2 ~] $crsctl check ctssCRS-4701: The Cluster Time Synchronization Service is in Active mode.CRS-4702: Offset (in msec): 0 [grid@jytest2 ~] $cluvfy comp clocksync-n allVerifying Clock Synchronization... PASSEDVerification of Clock Synchronization across the cluster nodes was successful.CVU operation performed: Clock Synchronization across the cluster nodesDate: Mar 3 2018 1:15:14 AMCVU home: / u01/app/product/12.2.0/crs/User: grid

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.