Cascade Standby
SUMMARY
1. logical standby不支持cascading standby
2. 11.2.0.2之前版本cascading standby不支持RAC
3. 11.2.0.3之前版本DG Broker環境不支持cascaded standby
DETAILS
為了減少primary system負載,減少帶寬需求,當需要配置多個standby時,可以采用cascade standby.
受支持的Cascading standby模式:
1. Primary DB > Physical Standby DB with cascaded destination > Physical Standby DB
2. Primary DB > Physical Standby DB with cascaded destination > Logical Standby DB
11.2.0.2之前,物理standby最多支持9個remote destination,11.2.0.2及之後最多支持30個。當物理standby配置了cascaded destination,在物理standby standby log滿時或者歸檔後,將傳輸這些從primary接受的redo到第二個standby上。第二個standby與primary之間必定有lag存在。cascaded standby可用作非實時的報表系統。
配置Cascaded Destination
1.在standby創建standby redo logfile
2.在primary設定LOG_ARCHIVE_DEST_n參數,設定physical standby轉發redo到cascaded destination.
定義傳輸模式:LGWR ASYNC或LGWR SYNC
設定VALID_FOR屬性啟用redo轉發
3.轉發redo的physical standby開啟歸檔模式
4.配置轉發redo的physical standby LOG_ARCHIVE_DEST_n參數
參數配置案例:
Boston Database (Primary Role):
DB_UNIQUE_NAME=boston
STANDBY_ARCHIVE_DEST=/arch1/boston/
REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE
LOG_ARCHIVE_CONFIG=‘DG_CONFIG=(chicago,boston,denver)‘
LOG_ARCHIVE_DEST_1=‘LOCATION=/arch1/boston/ VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=boston‘
LOG_ARCHIVE_DEST_2= ‘SERVICE=denver VALID_FOR=(STANDBY_LOGFILES,STANDBY_ROLE) DB_UNIQUE_NAME=denver‘
LOG_ARCHIVE_DEST_3=‘SERVICE=chicago VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=chicago‘
Chicago Database (Standby Role):
DB_UNIQUE_NAME=chicago
LOG_ARCHIVE_CONFIG=‘DG_CONFIG=(chicago,boston,denver)‘
STANDBY_ARCHIVE_DEST=/arch1/chicago/
REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE
LOG_ARCHIVE_DEST_1=‘LOCATION=/arch1/chicago/ VALID_FOR=(ONLINE_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=chicago‘
LOG_ARCHIVE_DEST_2=‘SERVICE=denver VALID_FOR=(STANDBY_LOGFILES,STANDBY_ROLE) DB_UNIQUE_NAME=denver‘
LOG_ARCHIVE_DEST_3=‘SERVICE=boston VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=boston‘
Denver Database (Standby Role):
DB_UNIQUE_NAME=denver
LOG_ARCHIVE_CONFIG=‘DG_CONFIG=(chicago,boston,denver)‘
STANDBY_ARCHIVE_DEST=/arch2/denver/ <====For Logical Standby
REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE
LOG_ARCHIVE_DEST_1=‘LOCATION=/arch1/denver/ VALID_FOR=(ONLINE_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=denver‘
LOG_ARCHIVE_DEST_2=‘LOCATION=/arch2/denver/ VALID_FOR=(STANDBY_LOGFILES,STANDBY_ROLE) DB_UNIQUE_NAME=denver‘
角色轉變
Oracle建議主要用於災難恢復的備份數據庫直接接收重做數據從主數據庫,數據保護可達到最佳水平。級聯standby可以作防禦的第二線,但其總是比primary延遲。
Cascade Standby