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 程式師世界 >> 數據庫知識 >> Oracle數據庫 >> Oracle教程 >> DGbroker三種保護模式的切換,dgbroker保護模式

DGbroker三種保護模式的切換,dgbroker保護模式

編輯:Oracle教程

DGbroker三種保護模式的切換,dgbroker保護模式


1.三種保護模式

  – Maximum protection

在Maximum protection下, 可以保證從庫和主庫數據完全一樣,做到zero data loss.事務同時在主從兩邊提交完成,才算事務完成。如果從庫宕機或者網絡出現問題,主從庫不能通訊,主庫也立即宕機。在這種方式下,具有最高的保護等級。但是這種模式對主庫性能影響很大,要求高速的網絡連接。

  – Maximum availability

在Maximum availability模式下,如果和從庫的連接正常,運行方式等同Maximum protection模式,事務也是主從庫同時提交。如果從庫和主庫失去聯系,則主庫自動切換到Maximum performance模式下運行,保證主庫具有最大的可用性。

  – Maximum performance

在Maximum performance,主庫把歸檔的 archived log通過arch進程傳遞給從庫,在這種方式下,主庫運行性能最高,但是不能保證數據不丟失,且丟失的數據受redo log的大小影響。在redo log過大的情況下,可能一天都沒有歸檔一個日志,可以通過手工切換日志的方式來減小數據的丟失。

2.模式切換(Maximum performance切換至Maximum availability)

  a.查看保護的模式

     DGbroker查看:

DGMGRL> show configuration  verbose;

Configuration - dgc

  Protection Mode: MaxPerformance
  Databases:
    atest1 - Primary database
    atest2 - Physical standby database

  Properties:
    FastStartFailoverThreshold      = '30'
    OperationTimeout                = '30'
    FastStartFailoverLagLimit       = '30'
    CommunicationTimeout            = '180'
    ObserverReconnect               = '0'
    FastStartFailoverAutoReinstate  = 'TRUE'
    FastStartFailoverPmyShutdown    = 'TRUE'
    BystandersFollowRoleChange      = 'ALL'
    ObserverOverride                = 'FALSE'
    ExternalDestination1            = ''
    ExternalDestination2            = ''
    PrimaryLostWriteAction          = 'CONTINUE'

Fast-Start Failover: DISABLED

Configuration Status:
SUCCESS

     sqlplus查看:

SQL> select database_role,protection_mode,protection_level from v$database;

DATABASE_ROLE     PROTECTION_MODE      PROTECTION_LEVEL
---------------- -------------------- --------------------
PRIMARY      MAXIMUM PERFORMANCE  MAXIMUM PERFORMANCE

  b.查看備庫的日志傳輸模式(參數LogXptMode(sync:同步傳輸/async:異步傳輸))

DGMGRL> show database verbose 'atest2';

Database - atest2

  Role:            PHYSICAL STANDBY
  Intended State:  APPLY-ON
  Transport Lag:   0 seconds (computed 1 second ago)
  Apply Lag:       0 seconds (computed 1 second ago)
  Apply Rate:      97.00 KByte/s
  Real Time Query: ON
  Instance(s):
    atest

  Properties:
    DGConnectIdentifier             = 'atest2'
    ObserverConnectIdentifier       = ''
    LogXptMode                      = 'sync'
    DelayMins                       = '0'
    Binding                         = 'optional'
    MaxFailure                      = '0'
    MaxConnections                  = '1'
    ReopenSecs                      = '300'
    NetTimeout                      = '30'
    RedoCompression                 = 'DISABLE'
    LogShipping                     = 'ON'
    PreferredApplyInstance          = ''
    ApplyInstanceTimeout            = '0'
    ApplyParallel                   = 'AUTO'
    StandbyFileManagement           = 'AUTO'
    ArchiveLagTarget                = '0'
    LogArchiveMaxProcesses          = '4'
    LogArchiveMinSucceedDest        = '1'
    DbFileNameConvert               = ''
    LogFileNameConvert              = ''
    FastStartFailoverTarget         = ''
    InconsistentProperties          = '(monitor)'
    InconsistentLogXptProps         = '(monitor)'
    SendQEntries                    = '(monitor)'
    LogXptStatus                    = '(monitor)'
    RecvQEntries                    = '(monitor)'
    ApplyLagThreshold               = '0'
    TransportLagThreshold           = '0'
    TransportDisconnectedThreshold  = '30'
    SidName                         = 'atest'
    StaticConnectIdentifier         = '(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=vijay02.database.com)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=atest2_DGMGRL)(INSTANCE_NAME=atest)(SERVER=DEDICATED)))'
    StandbyArchiveLocation          = '/u01/app/oracle/oradata/ATEST/archivelog'
    AlternateLocation               = ''
    LogArchiveTrace                 = '0'
    LogArchiveFormat                = '%t_%s_%r.dbf'
    TopWaitEvents                   = '(monitor)'

Database Status:
SUCCESS

  c.如果LogXptMode的值為async,就要將其修改為sync

DGMGRL> edit database atest1 set property logxptmode=sync;
Property "logxptmode" updated

  d.修改完之後再次確認LogXptMode的值,如步驟b

  e.切換模式(如果切換失敗,則再次去確認備庫LogXptMode的值)

DGMGRL> edit configuration set protection mode as maxavailability;
Succeeded.

  f. 確認數據庫的的保護模式,如步驟a

  g.需要注意的是,步驟c中修改的sync是備庫的值,切記!

 3.個人小結:

  a.三種模式在可以在DGbroker中自由切換(使用步驟2的方式)(在測試庫中),正常情況下,數據庫能迅速反應過來(查看保護模式的時候)。

  b.使用Maximum performance的時候,參數(備庫)LogXptMode設置為async就好/

  c.使用Maximum protection或者Maximum availability的時候,參數(備庫)LogXptMode要設置為sync。

  d.(經測試)使用Maximum protection時,當備庫出現異常(如網絡問題,數據庫宕機),主庫會掛起(告警日志會報如下錯誤),當備庫恢復正常之後,主庫也會恢復。

LGWR: Error 1034 attaching to RFS for reconnect

  e.使用Maximum protection時,在當備庫出現異常的情況下,當主庫掛起時,(主庫)可以強制切換到 Maximum performance,但當重新切回Maximum protection(在備庫恢復時),主庫需重啟。

DGMGRL> edit configuration set protection mode as maxprotection;
Operation requires shutdown of instance "atest" on database "atest1"
Shutting down instance "atest"...
Unable to connect to database
ORA-12545: Connect failed because target host or object does not exist

Failed.
Warning: You are no longer connected to ORACLE.

Please complete the following steps to finish the operation:
    shut down instance "atest" of database "atest1"
    start up instance "atest" of database "atest1"

 

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