结论1：主库和master ob 挂掉，不会fofo! DGMGRL> SHOW OBSERVERS ObserverConfigFile=observer.ora observer configuration file parsing succeeded Submitted command "SHOW OBSERVER" using connect identifier "orcl" Connected to "orcl" Configuration - dg_config Primary: orcl Active Target: orcl2dg Observer "grp_a" - Master Host Name: prdb19 Last Ping to Primary: 0 seconds ago Last Ping to Target: 3 seconds ago Observer "grp_b" - Backup Host Name: prdg19 Last Ping to Primary: 2 seconds ago Last Ping to Target: 2 seconds ago . Submitted command "SHOW OBSERVER" using connect identifier "orcl2dg" Connected to "orcl2dg" Configuration - dg_config Primary: orcl Active Target: orcl2dg Observer "grp_a" - Master Host Name: prdb19 Last Ping to Primary: 2 seconds ago Last Ping to Target: 2 seconds ago Observer "grp_b" - Backup Host Name: prdg19 Last Ping to Primary: 1 second ago Last Ping to Target: 1 second ago . Submitted command "SHOW OBSERVER" using connect identifier "orcl0dg" Connected to "orcl0dg" Configuration - dg_config Primary: orcl Active Target: orcl2dg Observer "grp_a" - Master Host Name: prdb19 Last Ping to Primary: 2 seconds ago Last Ping to Target: 2 seconds ago Observer "grp_b" - Backup Host Name: prdg19 Last Ping to Primary: 1 second ago Last Ping to Target: 2 seconds ago DGMGRL> SHOW CONFIGURATION lag verbose Configuration - dg_config Protection Mode: MaxPerformance Members: orcl - Primary database orcl2dg - (*) Physical standby database Transport Lag: 0 seconds (computed 0 seconds ago) Apply Lag: 0 seconds (computed 0 seconds ago) orcl0dg - Physical standby database Transport Lag: 0 seconds (computed 0 seconds ago) Apply Lag: 0 seconds (computed 0 seconds ago) (*) Fast-Start Failover target Properties: FastStartFailoverThreshold = '30' OperationTimeout = '30' TraceLevel = 'USER' FastStartFailoverLagLimit = '30' CommunicationTimeout = '180' ObserverReconnect = '0' FastStartFailoverAutoReinstate = 'TRUE' FastStartFailoverPmyShutdown = 'TRUE' BystandersFollowRoleChange = 'ALL' ObserverOverride = 'FALSE' ExternalDestination1 = '' ExternalDestination2 = '' PrimaryLostWriteAction = 'CONTINUE' ConfigurationWideServiceName = 'orcl_CFG' Fast-Start Failover: Enabled in Potential Data Loss Mode Lag Limit: 30 seconds Threshold: 30 seconds Active Target: orcl2dg Potential Targets: "orcl2dg" orcl2dg valid Observers: (*) grp_a grp_b Shutdown Primary: TRUE Auto-reinstate: TRUE Observer Reconnect: (none) Observer Override: FALSE Configuration Status: SUCCESS DGMGRL> 经验分享：不要随意操作broker ，并发行不好，返回机制容易卡和行！尽量用视图获取数据！ --broker 数据无正常返回： [root@prdg19 ~]# su - oracle Last login: Sat Oct 12 22:10:17 CST 2024 on pts/2 [oracle@prdg19 rdbms]$ dgmgrl sys/Szcmb123_ DGMGRL for Linux: Release 19.0.0.0.0 - Production on Sat Oct 12 22:14:53 2024 Version 19.3.0.0.0 Copyright (c) 1982, 2019, Oracle and/or its affiliates. All rights reserved. Welcome to DGMGRL, type "help" for information. Connected to "orcl2dg" Connected as SYSDBA. DGMGRL> SHOW CONFIGURATION lag verbose --Fast-Start Failover is not possible 因为没有master observer【结论，没有设置参数，不会切换】 Unable to connect to database using prdb19/orcl [W000 2024-10-12T22:16:31.128+08:00] Primary database cannot be reached. [W000 2024-10-12T22:16:31.128+08:00] Fast-Start Failover threshold has not exceeded. Retry for the next 1 second [W000 2024-10-12T22:16:31.128+08:00] Try to connect to the primary. [W000 2024-10-12T22:16:34.131+08:00] Primary database cannot be reached. [W000 2024-10-12T22:16:34.131+08:00] Fast-Start Failover threshold has expired. [W000 2024-10-12T22:16:34.131+08:00] Try to connect to the standby. [W000 2024-10-12T22:16:34.131+08:00] Making a last connection attempt to primary database before proceeding with Fast-Start Failover. [W000 2024-10-12T22:16:34.131+08:00] Check if the standby is ready for failover. ORA-12543: TNS:destination host unreachable Unable to connect to database using prdb19/orcl [W000 2024-10-12T22:16:34.143+08:00] Fast-Start Failover is not possible because this observer is not the master. [W000 2024-10-12T22:16:35.144+08:00] Try to connect to the primary. ORA-12543: TNS:destination host unreachable Unable to connect to database using prdb19/orcl ORA-12543: TNS:destination host unreachable Unable to connect to database using prdb19/orcl [W000 2024-10-12T22:16:37.149+08:00] Primary database cannot be reached. [W000 2024-10-12T22:16:37.149+08:00] Try to connect to the primary. ORA-12543: TNS:destination host unreachable Unable to connect to database using prdb19/orcl --主库主机重启后，不会启动 DGMGRL> SHOW CONFIGURATION lag verbose Configuration - dg_config Protection Mode: MaxPerformance Members: orcl - Primary database Error: ORA-16810: multiple errors or warnings detected for the member orcl2dg - (*) Physical standby database Error: ORA-16825: multiple errors or warnings, including fast-start failover-related errors or warnings, detected for the database Transport Lag: 8 minutes 43 seconds (computed 2 seconds ago) Apply Lag: 8 minutes 43 seconds (computed 2 seconds ago) orcl0dg - Physical standby database Warning: ORA-16857: member disconnected from redo source for longer than specified threshold Transport Lag: 8 minutes 43 seconds (computed 2 seconds ago) Apply Lag: 8 minutes 43 seconds (computed 2 seconds ago) --连接主库后，才能看到observer 的failover, 没有发现fsfo DGMGRL> show observer Configuration - dg_config Primary: orcl Active Target: orcl2dg Observer "grp_b" - Master Host Name: prdg19 Last Ping to Primary: 0 seconds ago Last Ping to Target: 1 second ago Observer "grp_a" - Backup Host Name: prdb19 Last Ping to Primary: (unknown) Last Ping to Target: (unknown)
--解决方案[不可行]： 没有设置参数！测试结果同上，但是发现，主库启动后，ob failover,而且发生fsfo,风险较大！ EDIT CONFIGURATION SET PROPERTY ObserverReconnect=5; EDIT CONFIGURATION SET PROPERTY ObserverOverride=TRUE; --同样的报错 Unable to connect to database using prdb19/orcl [W000 2024-10-12T22:51:57.905+08:00] Fast-Start Failover is not possible because this observer is not the master. [W000 2024-10-12T22:51:58.906+08:00] Try to connect to the primary. ORA-12543: TNS:destination host unreachable Unable to connect to database using prdb19/orcl ORA-12543: TNS:destination host unreachable Unable to connect to database using prdb19/orcl [W000 2024-10-12T22:52:00.917+08:00] Primary database cannot be reached. [W000 2024-10-12T22:52:00.917+08:00] Try to connect to the primary. ORA-12543: TNS:destination host unreachable Unable to connect to database using prdb19/orcl --下面程序没有成功 set serveroutput on declare status integer; begin status := dbms_dg.initiate_fs_failover('Failover Requested'); dbms_output.put_line('Fast-Start Failover is disabled: Expected status = ORA-16646'); dbms_output.put_line(' Actual Status = ORA-' || status); end; / exit;
