Oracle集群（RAC）时间同步（ntp和CTSS）
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Oracle集群（RAC）时间同步（ntp和CTSS）
http://blog.itpub.net/26736162/viewspace-2157130/
crsctl stat res -t -init
ps -ef|grep ctss
crsctl check ctss
cluvfy comp clocksync -n all -verbose
crsctl start res ora.ctssd -init
crsctl stop res ora.ctssd -init
Network Time Protocol Setting
l You have two options for time synchronization: an operating system configured network time protocol (NTP), or Oracle Cluster Time Synchronization Service.
l Oracle Cluster Time Synchronization Service is designed for organizations whose cluster servers are unable to access NTP services.
l If you use NTP, then the Oracle Cluster Time Synchronization daemon (ctssd) starts up in observer mode. If you do not have NTP daemons, then ctssd starts up in active mode and synchronizes time among cluster members without contacting an external time server..
可以采用操作系统的NTP服务，也可以使用Oracle自带的服务ctss，如果ntp没有启用，那么Oracle会自动启用自己的ctssd进程。
从oracle 11gR2 RAC开始使用Cluster Time Synchronization Service(CTSS)同步各节点的时间,当安装程序发现NTP协议处于非活动状态时，安装集群时间同步服务将以活动模式（active）自动进行安装并同步所有节点的时间。如果发现配置了 NTP，则以观察者模式（observer mode）启动集群时间同步服务，Oracle Clusterware不会在集群中进行活动的时间同步。
在RAC中，集群的时间应该是保持同步的，否则可能导致很多问题，例如：依赖于时间的应用会造成数据的错误，各种日志打印的顺序紊乱，这将会影响问题的诊断，严重的可能会导致集群宕机或者重新启动集群时节点无法加入集群。
在Oracle 11gR2前，集群的时间是由NTP同步的，而在11gR2后，Oracle引入了CTSS组件，如果系统没有配置NTP，则由CTSS来同步集群时间。
NTP和CTSS是可以共存的，且NTP的优先级要高于CTSS，也就是说，如果系统中同时有NTP和CTSS，那么集群的时间是由NTP同步的，CTSS会处于观望（Observer）模式，只有当集群关闭所有的NTP服务，CTSS才会处于激活（Active）模式。在一个集群中，只要有一个节点的ntp处于活动状态，那么集群的所有节点的CTSS都会处于激活（Active）模式。
需要注意的是，要让CTSS处于激活（Active）模式，则不仅要关闭ntp服务（/sbin/service ntpd stop），还要删除/etc/ntp.conf文件（mv /etc/ntp.conf /etc/ntp.conf.bak），否则不能启用CTSS。
1.1.1 CTSS同步模式
关闭NTP：
/sbin/service ntpd stop
mv /etc/ntp.conf /etc/ntp.conf.bak
service ntpd status
chkconfig ntpd off
[root@raclhr-11gR2-N2 ~]# ps -ef|grep ctss
root 19678 1 0 19:22 ? 00:00:02 /u01/app/11.2.0/grid/bin/octssd.bin reboot
root 20970 20623 0 19:35 pts/4 00:00:00 grep ctss
[root@raclhr-11gR2-N2 ~]#
[root@raclhr-11gR2-N2 ~]# crsctl stat res -t -init
--------------------------------------------------------------------------------
NAME TARGET STATE SERVER STATE_DETAILS
--------------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------------
ora.asm
1 ONLINE ONLINE raclhr-11gr2-n2 Started
ora.cluster_interconnect.haip
1 ONLINE ONLINE raclhr-11gr2-n2
ora.crf
1 ONLINE ONLINE raclhr-11gr2-n2
ora.crsd
1 ONLINE ONLINE raclhr-11gr2-n2
ora.cssd
1 ONLINE ONLINE raclhr-11gr2-n2
ora.cssdmonitor
1 ONLINE ONLINE raclhr-11gr2-n2
ora.ctssd
1 ONLINE ONLINE raclhr-11gr2-n2 ACTIVE:0
ora.diskmon
1 OFFLINE OFFLINE
ora.evmd
1 ONLINE ONLINE raclhr-11gr2-n2
ora.gipcd
1 ONLINE ONLINE raclhr-11gr2-n2
ora.gpnpd
1 ONLINE ONLINE raclhr-11gr2-n2
ora.mdnsd
1 ONLINE ONLINE raclhr-11gr2-n2
[root@raclhr-11gR2-N2 ~]#
节点1的ctss状态：
[root@raclhr-11gR2-N1 ~]# crsctl check ctss
CRS-4701: The Cluster Time Synchronization Service is in Active mode.
CRS-4702: Offset (in msec): 0
[root@raclhr-11gR2-N1 ~]#
节点1的octssd的日志：
/u01/app/11.2.0/grid/log/raclhr-11gr2-n1/ctssd/octssd.log
2018-06-30 19:25:56.369: [ CTSS][899475200]sclsctss_gvss2: NTP default pid file not found
2018-06-30 19:25:56.369: [ CTSS][899475200]sclsctss_gvss8: Return [0] and NTP status [1].
2018-06-30 19:25:56.369: [ CTSS][899475200]ctss_check_vendor_sw: Vendor time sync software is not detected. status [1].
2018-06-30 19:25:57.002: [ CTSS][916338432]ctss_checkcb: clsdm requested check alive. checkcb_data{mode[0xcc], offset[0 ms]}, length=[8].
2018-06-30 19:26:01.263: [ CTSS][901576448]ctsscomm_recv_cb2: Receive incoming message event. Msgtype [1].
2018-06-30 19:26:01.264: [ CTSS][901576448]ctsscomm_msg_hndlr: Received sync msg
2018-06-30 19:26:01.264: [ CTSS][901576448]ctsscomm_msg_hndlr: Received from slave ( mode [0xc4] nodenum [2] hostname [raclhr-11gr2-n2] )
2018-06-30 19:26:09.267: [ CTSS][901576448]ctsscomm_recv_cb2: Receive incoming message event. Msgtype [1].
节点1的octssd.log中记录没有发现ntp服务，ctss服务为激活模式。
节点2的ctss状态：
[root@raclhr-11gR2-N2 ~]# crsctl check ctss
CRS-4701: The Cluster Time Synchronization Service is in Active mode.
CRS-4702: Offset (in msec): 0
[root@raclhr-11gR2-N2 ~]#
节点2的octssd的日志：
/u01/app/11.2.0/grid/log/raclhr-11gr2-n2/ctssd/octssd.log
2018-06-30 19:28:49.539: [ CTSS][839321344]sclsctss_gvss2: NTP default pid file not found
2018-06-30 19:28:49.539: [ CTSS][839321344]sclsctss_gvss8: Return [0] and NTP status [1].
2018-06-30 19:28:49.539: [ CTSS][839321344]ctss_check_vendor_sw: Vendor time sync software is not detected. status [1].
2018-06-30 19:29:05.544: [ CTSS][839321344]ctsselect_msm: CTSS mode is [0xc4]
2018-06-30 19:29:05.544: [ CTSS][839321344]ctssslave_swm1_2: Ready to initiate new time sync process.
2018-06-30 19:29:05.545: [ CTSS][839321344]ctssslave_swm2_1: Waiting for time sync message from master. sync_state[2].
2018-06-30 19:29:05.546: [ CTSS][845625088]ctsscomm_recv_cb2: Receive incoming message event. Msgtype [2].
2018-06-30 19:29:05.546: [ CTSS][845625088]ctssslave_msg_handler4_1: Waiting for slave_sync_with_master to finish sync process. sync_state[3].
2018-06-30 19:29:05.547: [ CTSS][839321344]ctssslave_swm2_3: Received time sync message from master.
2018-06-30 19:29:05.547: [ CTSS][839321344]ctssslave_swm: The system time difference is too small [243] usec. Not adjusting time.
2018-06-30 19:29:05.547: [ CTSS][839321344]ctssslave_swm17: LT [1530358145sec 546888usec], MT [1530358145sec 140655884523349usec], Delta [2314usec]
2018-06-30 19:29:05.547: [ CTSS][839321344]ctssslave_swm19: The offset is [243 usec] and sync interval set to [1]
2018-06-30 19:29:05.547: [ CTSS][839321344]ctssslave_swm: Received from master (mode [0xcc] nodenum [1] hostname [raclhr-11gr2-n1] )
2018-06-30 19:29:05.547: [ CTSS][839321344]ctsselect_msm: Sync interval returned in [1]
2018-06-30 19:29:05.547: [ CTSS][845625088]ctssslave_msg_handler4_3: slave_sync_with_master finished sync process. Exiting clsctssslave_msg_handler
2018-06-30 19:29:07.910: [ CTSS][860387072]ctss_checkcb: clsdm requested check alive. checkcb_data{mode[0xc4], offset[0 ms]}, length=[8].
节点2的octssd.log中记录没有发现ntp服务，ctss服务为激活模式，同步时间的主节点是节点1，并且会告诉集群的时间有差异，但是因为差异过小，无需调整。
校验集群的时间：
cluvfy comp clocksync -n all -verbose
虽然集群时间不一致，但是这种情况下校验结果是通过的，而且略微的差异范围内集群也会自动同步回来。
[grid@raclhr-11gR2-N1 ~]$ cluvfy comp clocksync -n all -verbose
Verifying Clock Synchronization across the cluster nodes
Checking if Clusterware is installed on all nodes...
Check of Clusterware install passed
Checking if CTSS Resource is running on all nodes...
Check: CTSS Resource running on all nodes
Node Name Status
------------------------------------ ------------------------
raclhr-11gr2-n2 passed
raclhr-11gr2-n1 passed
Result: CTSS resource check passed
Querying CTSS for time offset on all nodes...
Result: Query of CTSS for time offset passed
Check CTSS state started...
Check: CTSS state
Node Name State
------------------------------------ ------------------------
raclhr-11gr2-n2 Active
raclhr-11gr2-n1 Active
CTSS is in Active state. Proceeding with check of clock time offsets on all nodes...
Reference Time Offset Limit: 1000.0 msecs
Check: Reference Time Offset
Node Name Time Offset Status
------------ ------------------------ ------------------------
raclhr-11gr2-n2 0.0 passed
raclhr-11gr2-n1 0.0 passed
Time offset is within the specified limits on the following set of nodes:
"[raclhr-11gr2-n2, raclhr-11gr2-n1]"
Result: Check of clock time offsets passed
Oracle Cluster Time Synchronization Services check passed
Verification of Clock Synchronization across the cluster nodes was successful.
1.1.2 NTP同步模式
开启NTP:
mv /etc/ntp.conf.bak /etc/ntp.conf
service ntpd status
/sbin/service ntpd start
# chkconfig ntpd off
ps -ef|grep ntp
节点1 ：
[root@raclhr-11gR2-N1 ~]# crsctl check ctss
CRS-4700: The Cluster Time Synchronization Service is in Observer mode.
[root@raclhr-11gR2-N1 ~]# crsctl stat res -t -init
ora.ctssd
1 ONLINE ONLINE raclhr-11gr2-n1 OBSERVER
节点1的ctss日志：
/u01/app/11.2.0/grid/log/raclhr-11gr2-n1/ctssd/octssd.log
2018-06-30 20:51:29.388: [ CTSS][899475200]sclsctss_gvss1: NTP default config file found
2018-06-30 20:51:29.389: [ CTSS][899475200]sclsctss_gvss8: Return [0] and NTP status [2].
2018-06-30 20:51:29.389: [ CTSS][899475200]ctss_check_vendor_sw: Vendor time sync software is detected. status [2].
2018-06-30 20:51:29.389: [ CTSS][899475200]ctss_check_vendor_sw: Ctssd is switching to observer role
2018-06-30 20:51:29.389: [ CTSS][899475200]clsctsselect_update_mbrdata: Updating pridata: { version[1] node[1] swversion[186647296] mode[0xee] }.
2018-06-30 20:51:29.639: [ CRSCCL][671086336]clsCclGetPriMemberData: Detected pridata change for node[1]. Retrieving it to the cache.
2018-06-30 20:51:31.434: [ CTSS][916338432]ctss_checkcb: clsdm requested check alive. checkcb_data{mode[0xee], offset[0 ms]}, length=[8].
2018-06-30 20:51:35.258: [ CTSS][901576448]ctsscomm_recv_cb2: Receive incoming message event. Msgtype [1].
2018-06-30 20:51:35.258: [ CTSS][901576448]ctsscomm_msg_hndlr: Received sync msg
2018-06-30 20:51:35.259: [ CTSS][901576448]ctsscomm_msg_hndlr: Received from slave ( mode [0xc4] nodenum [2] hostname [raclhr-11gr2-n2] )
2018-06-30 20:51:35.656: [ CRSCCL][671086336]clsCclGetPriMemberData: Detected pridata change for node[2]. Retrieving it to the cache.
2018-06-30 20:51:43.240: [ CTSS][901576448]ctsscomm_recv_cb2: Receive incoming message event. Msgtype [1].
2018-06-30 20:51:43.240: [ CTSS][901576448]ctsscomm_msg_hndlr: Received sync msg
2018-06-30 20:51:43.240: [ CTSS][901576448]ctsscomm_msg_hndlr: Received from slave ( mode [0xc6] nodenum [2] hostname [raclhr-11gr2-n2] )
2018-06-30 20:51:51.217: [ CTSS][901576448]ctsscomm_recv_cb2: Receive incoming message event. Msgtype [1].
2018-06-30 20:51:51.217: [ CTSS][901576448]ctsscomm_msg_hndlr: Received sync msg
2018-06-30 20:51:51.218: [ CTSS][901576448]ctsscomm_msg_hndlr: Received from slave ( mode [0xc6] nodenum [2] hostname [raclhr-11gr2-n2] )
2018-06-30 20:51:59.194: [ CTSS][901576448]ctsscomm_recv_cb2: Receive incoming message event. Msgtype [1].
2018-06-30 20:51:59.194: [ CTSS][901576448]ctsscomm_msg_hndlr: Received sync msg
2018-06-30 20:51:59.195: [ CTSS][901576448]ctsscomm_msg_hndlr: Received from slave ( mode [0xc6] nodenum [2] hostname [raclhr-11gr2-n2] )
节点1的octssd.log中记录发现ntp服务，ctss服务会自动切换到观望模式。
2018-06-30 20:57:27.608: [ CTSS][839321344]ctsselect_msm: CTSS mode is [0xc6]
2018-06-30 20:57:27.608: [ CTSS][839321344]ctssslave_swm1_2: Ready to initiate new time sync process.
2018-06-30 20:57:27.609: [ CTSS][839321344]ctssslave_swm2_1: Waiting for time sync message from master. sync_state[2].
2018-06-30 20:57:27.612: [ CTSS][845625088]ctsscomm_recv_cb2: Receive incoming message event. Msgtype [2].
2018-06-30 20:57:27.613: [ CTSS][845625088]ctssslave_msg_handler4_1: Waiting for slave_sync_with_master to finish sync process. sync_state[3].
2018-06-30 20:57:27.613: [ CTSS][839321344]ctssslave_swm2_3: Received time sync message from master.
2018-06-30 20:57:27.613: [ CTSS][839321344]ctssslave_swm17: LT [1530363447sec 613028usec], MT [1530363447sec 140655884569984usec], Delta [4410usec]
2018-06-30 20:57:27.613: [ CTSS][839321344]ctssslave_swm19: The offset is [19748 usec] and sync interval set to [1]
2018-06-30 20:57:27.613: [ CTSS][839321344]ctssslave_swm: Received from master (mode [0xee] nodenum [1] hostname [raclhr-11gr2-n1] )
2018-06-30 20:57:27.613: [ CTSS][839321344]ctsselect_msm: Sync interval returned in [1]
2018-06-30 20:57:27.613: [ CTSS][845625088]ctssslave_msg_handler4_3: slave_sync_with_master finished sync process. Exiting clsctssslave_msg_handler
节点2的octssd.log中也会记录发现ntp服务，ctss服务为观望模式，并且同步时间的主节点是节点1。
1.1.3 模拟集群时间不一致
如果在我们生产系统中碰到集群时间不一致会导致什么结果，我们的排查思路是怎么样的，以下是模拟集群时间不一致的场景。
更改节点2的时间，向后推移2天：
将系统时间设定成2018年07月02日的命令如下：
#date -s 07/02/2018
将系统时间设定成下午23点23分06秒的命令如下。
#date -s 23:23:06
[root@raclhr-11gR2-N2 ctssd]# crsctl stat res -t -init
ora.ctssd
1 ONLINE ONLINE raclhr-11gr2-n2 ACTIVE:172768000
[root@raclhr-11gR2-N2 ctssd]# crsctl check ctss
CRS-4701: The Cluster Time Synchronization Service is in Active mode.
CRS-4702: Offset (in msec): 172768000
172768000微妙大约为2天:
SYS@lhrrac11> select 172768000/1000/24/60/60 from dual;
172768000/1000/24/60/60
-----------------------
1.99962963
更改节点2的时间后，在ASM和DB的alert日志中产生了以下的告警信息：
Time drift detected. Please check VKTM trace file for more details.
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