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故障分析:11GR DATAGRUAD环境BROKER配置Fast-Start Failover
FAST-START failover 就是在当主数据库出现故障时,能快速与可靠的把standby切换成主数据库,在整个过程中不需要人来干预。fast-start failover只能通过dgmgrl与Enterprise Managerg来配置。
只有maximum availability mode or maximum performance mode才能启用fast-start failover模式。在maximum availability模式下面,在切换时可以保证无数据丢失,在maximum performance mode下面,会有数据丢失,丢失多少数据由 FastStartFailoverLagLimit这个参数来配置。
只要observer进程启动过,我们就不需要人为的干预。当observer与指定的备数据库与主数据库失去连接的时间超过FastStartFailoverThreshold后,observer就会启动fast-start failover 到备数据库。如果配置了FastStartFailoverPmyShutdown为true,此时原来的主数据库将会自动的shutdown。如果配置FastStartFailoverAutoReinstate为true,当failover完成后,启动数据库时,会自动的执行Reinstate database,把原来的主数据库变成备库,并与新主库进行同步。
fast-start failover包含3个过程,如下图:
测试开始:
环境:OS REDHAT 5.6 X86_64 ,DB 11.2.0.2
1,DG环境的搭建。
见11GR2 搭建活动的物理DG/DATAGRUAD (READ ONLY模式)
2,broker的配置
3,配置保护模式与日志传递方式
之前已经说了FAST-START FAILOVER只 maximum availability mode与maximum performance mode
下面我们看一下每一种保护模式对应的日志传递方式。
3.1修改保护模式:
[oracle@test admin]$ dgmgrl
DGMGRL for Linux: Version 11.2.0.2.0 - 64bit Production Copyright (c) 2000, 2009, Oracle. All rights reserved. Welcome to DGMGRL, type "help" for information.
DGMGRL> connect sys/oracle@htz
Connected.
#通过help查看命令的帮忙。
DGMGRL> help edit
Edits a configuration, database, or instance
Syntax: EDIT CONFIGURATION SET PROTECTION MODE AS {MaxProtection|MaxAvailability|MaxPerformance}; EDIT CONFIGURATION SET PROPERTY <property name> = <value>; EDIT DATABASE <database name> SET PROPERTY <property name> = <value>; EDIT DATABASE <database name> RENAME TO <new database name>; EDIT DATABASE <database name> SET STATE = <state> [WITH APPLY INSTANCE = <instance name>]; EDIT INSTANCE <instance name> [ON DATABASE <database name>] SET AUTO PFILE [ = {<initialization file path>|OFF} ]; EDIT INSTANCE <instance name> [ON DATABASE <database name>] SET PROPERTY <property name> = <value>; EDIT INSTANCE * ON DATABASE <database name> SET PROPERTY <property name> = <value>; DGMGRL> edit configuration set protection mode as maxavilability;
Syntax error before or at "maxavilability"
DGMGRL> show configuration; Configuration - htz
最大可用的保护模式
Protection Mode: MaxAvailability Databases: htzb - Primary database htz - Physical standby database
Fast-Start Failover: DISABLED
Configuration Status:
SUCCESS
3.2 修改日志传递方式
DGMGRL> edit database htz set property logxptmode=sync;
Property "logxptmode" updated
DGMGRL> edit database htzb set property logxptmode=sync;
Property "logxptmode" updated
DGMGRL> show database htz logxptmode LogXptMode = 'sync'
DGMGRL> show database htzb logxptmode LogXptMode = 'sync
4 配置数据库的flashback
4.1 主库上面
SQL> select open_mode,database_role,log_mode,flashback_on from v$database; OPEN_MODE DATABASE_ROLE LOG_MODE FLASHBACK_ON
-------------------- ---------------- ------------ ------------------
READ WRITE PRIMARY ARCHIVELOG NO
配置flashback
SQL> alter database flashback on; Database altered. SQL> select open_mode,database_role,log_mode,flashback_on from v$database; OPEN_MODE DATABASE_ROLE LOG_MODE FLASHBACK_ON
-------------------- ---------------- ------------ ------------------
READ WRITE PRIMARY ARCHIVELOG YES
flashback的配置目录与大小
SQL> show parameter recovery NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string /u01/app/oracle/fast_recovery_ area
db_recovery_file_dest_size big integer 4032M
4.2 备库上面
SQL> select open_mode,database_role,log_mode,flashback_on from v$database; OPEN_MODE DATABASE_ROLE LOG_MODE FLASHBACK_ON
-------------------- ---------------- ------------ ------------------
READ ONLY WITH APPLY PHYSICAL STANDBY ARCHIVELOG NO SQL> recover managed standby database cancel;
Media recovery complete.
SQL> alter database flashback on; Database altered. SQL> recover managed standby database using current logfile disconnect;
Media recovery complete.
SQL> select open_mode,database_role,log_mode,flashback_on from v$database; OPEN_MODE DATABASE_ROLE LOG_MODE FLASHBACK_ON
-------------------- ---------------- ------------ ------------------
READ ONLY WITH APPLY PHYSICAL STANDBY ARCHIVELOG YES
5 配置observer服务器
5.1 配置tnsnames.ora文件。
[oracle@test admin]$ cat tnsnames.ora
HTZB = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.100.31)(PORT = 1521)) ) (CONNECT_DATA = (SERVER = dedicate) (SERVICE_NAME = htzb) ) ) HTZ = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.100.30)(PORT = 1521)) ) (CONNECT_DATA = (SERVER = dedicate) (SERVICE_NAME = htz) ) )
5.2 启动observer进程
[oracle@test admin]$ dgmgrl sys/oracle@htz "start observer"
DGMGRL for Linux: Version 11.2.0.2.0 - 64bit Production Copyright (c) 2000, 2009, Oracle. All rights reserved. Welcome to DGMGRL, type "help" for information.
Connected.
Observer started
6 配置fast-start failover
DGMGRL> edit database htz set property FastStartFailoverTarget=htzb;
Property "faststartfailovertarget" updated
DGMGRL> edit database htzb set property FastStartFailoverTarget=htz;
Property "faststartfailovertarget" updated
于fst-start failove相关的其它几个参数:FastStartFailoverPmyShutdownFastStartFailoverLagLimitFastStartFailoverAutoReinstateObserverConnectIdentifier
这里我们都使用默认值;我们来看一下这些值的默认值;
DGMGRL> show configuration verbose; Configuration - htz Protection Mode: MaxAvailability Databases: htzb - Primary database htz - (*) Physical standby database (*) Fast-Start Failover target Properties: FastStartFailoverThreshold = '30' OperationTimeout = '30' FastStartFailoverLagLimit = '30' CommunicationTimeout = '180' FastStartFailoverAutoReinstate = 'TRUE' FastStartFailoverPmyShutdown = 'TRUE' BystandersFollowRoleChange = 'ALL' Fast-Start Failover: DISABLEThreshold: 30 seconds Target: htz Observer: test Lag Limit: 30 seconds (not in use) Shutdown Primary: TRUE Auto-reinstate: TRUE Configuration Status:
SUCCESS
7 启用fast-start failover
DGMGRL> show configuration Configuration - htz Protection Mode: MaxAvailability Databases: htzb - Primary database htz - Physical standby database Fast-Start Failover: DISABLED Configuration Status:
SUCCESS
DGMGRL> enable fast_start failover
Enabled.
DGMGRL>
8.测试FAST-START FAILOVER是否生效
DGMGRL> show configuration Configuration - htz Protection Mode: MaxAvailability Databases: htzb - Primary database htz - (*) Physical standby database
Fast-Start Failover: ENABLED
Configuration Status:
SUCCESS
原主库直接shutdown abort;
SQL> shutdown abort;
ORACLE instance shut down.
SQL>
observer进程的日志
19:03:03.93 Friday, September 07, 2012
Initiating Fast-Start Failover to database "htz"...
Performing failover NOW, please wait...
Failover succeeded, new primary is "htz"
19:03:13.24 Friday, September 07, 2012
提示已经把主切换到htz
在htz上面查看一下
SQL> select open_mode ,database_role from v$database; OPEN_MODE DATABASE_ROLE
-------------------- ----------------
READ WRITE PRIMARY
已经成功
手动启动原主库
DGMGRL> show configuration;Configuration - htzProtection Mode: MaxAvailabilityDatabases:htz - Primary databaseWarning: ORA-16817: unsynchronized fast-start failover configurationhtzb - (*) Physical standby database (disabled)ORA-16661: the standby database needs to be reinstatedFast-Start Failover: ENABLEDConfiguration Status:
WARNINGDGMGRL> connect sys/oracle@htzb
Connected.
DGMGRL> startup
ORACLE instance started.
Database mounted.
ORA-16649: possible failover to another database prevents this database from being opened
过一分会后我们再查看一下状态
DGMGRL> connect sys/oracle@htz
Connected.
DGMGRL> show configurationConfiguration - htzProtection Mode: MaxAvailabilityDatabases:htz - Primary databasehtzb - (*) Physical standby databaseFast-Start Failover: ENABLEDConfiguration Status:
SUCCESS
查看状态,一切正常。
------------------作者介绍-----------------------
姓名:黄廷忠
现就职:Oracle中国高级服务团队
曾就职:OceanBase、云和恩墨、东方龙马等
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