今天是2014-03-19，對oracle TAF技術整理一下學習筆記，記錄如下：
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failover_mode 參數 描述
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backup 指定用於創建備份連接的本地服務名，當使用preconnect預創建連接
的時候應該指明這個參數值
method TAF的配置包含如下兩種failover切換方式
preconnect：創建到切換實例的預連接，提供快速failover的能力
basic：在發生failover的時候創建連接
retries failover發生後嘗試連接的次數，如果指明了delay參數，那麼retries默認為5
type Taf的配置包含如下三種failover的類型：
session：如果用戶連接丟失，新的會話將自動被創建。這種類型的failover不能
嘗試恢復select操作
select：如果用戶連接丟失，新創建的會話將繼續之前失敗之後的select操作
none 這是默認值，不具備failover能力。這個能被明確的指明用於防止failover
的發生。
注意：這些參數只能手動設置，不能在listener.ora文件中SID_LIST_<LISTENER_NAME>條目中設置global_dbname參數，靜態配置的全局數據
庫名稱不能使用TAF功能。另外jdbc thin驅動方式無法使用TAF技術。
實現TAF有兩種方式一種為client-side TAF 另一種為server-side TAF ，下面先介紹第一種client-side TAF:
RAC =
(DESCRIPTION =
(FAILOVER=ON)
(LOAD_BALANCE=ON)
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = rac-one)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = rac-two)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = Rac2)
(FAILOVER_MODE=
(TYPE=SELECT)
(METHOD=BASIC))
)
)
該方式使用了連接時failover、client-side TAF 和客戶端負載均衡，當該客戶端嘗試連接數據庫的時候會在address中隨即挑選一個用於連接數據庫，假如選擇rac-one如果連接失敗，那麼就會使用rac-two進行連接，如果都失敗那麼將提出連接錯誤。當客戶端已經連接到數據庫的時候，突然rac-one實例關閉，那麼該客戶端隨即創建與rac-two的會話連接這個過程報錯select的操作。例外我們可以使用retries和delay參數來指定重新連接次數和延遲重新連接的秒數。如下是重試連接rac-one5次每次120秒。
eg：
RAC =
(DESCRIPTION =
(FAILOVER=ON)
(LOAD_BALANCE=OFF)
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = rac-one-vip)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = rac-two-vip)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = Rac2)
(FAILOVER_MODE=
(TYPE=SELECT)
(METHOD=BASIC)
(RETRIES=5)
(DELAY=120)
)
)
)
另外在failover_mode中的method中有preconnect（預連接），該說明在client-side TAF中分配一個主連接的同時預先分配備用連接。
eg：
RAC1 =
(DESCRIPTION =
(FAILOVER=ON)
(LOAD_BALANCE=OFF)
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = rac-one)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = Rac2)
(FAILOVER_MODE=
(METHOD=PRECONNECT)
(BACKUP=RAC2)
(TYPE=SELECT)
(RETRIES=5)
(DELAY=30)
)
)
)
RAC2 =
(DESCRIPTION =
(FAILOVER=ON)
(LOAD_BALANCE=OFF)
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = rac-two)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = Rac2)
(FAILOVER_MODE=
(METHOD=PRECONNECT)
(BACKUP=RAC1)
(TYPE=SELECT)
(RETRIES=5)
(DELAY=30)
)
)
)
驗證client-side TAF：
首先確認/etc/hosts文件如下：
[root@rac-one ~]# more /etc/hosts 127.0.0.1 localhost localhost.localdomain 192.168.2.11 openfiler1 192.168.1.112 rac-two-priv 192.168.1.111 rac-one-priv 192.168.4.111 rac-one rac-one.localdomain 192.168.4.112 rac-two rac-two.localdomain 192.168.4.113 rac-one-vip 192.168.4.114 rac-two-vip [root@rac-one ~]#
查看客戶端tnsname.ora配置：
RAC =
(DESCRIPTION =
(FAILOVER=ON)
(LOAD_BALANCE=ON)
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = rac-two-vip)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = rac-one-vip)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = Rac)
(FAILEOVER_MODE=
(METHOD=BASIC)
(TYPE=SELECT)
(RETRIES=5)
(DELAY=60))
)
)
用戶連接數據庫，然後查看數據庫會話信息，（注意還需要修改windows的hosts名稱否則無法識別rac-two-vip或是rac-one-vip）：
rac-one節點：
SQL> r
1 select inst_id,username,failover_type,failover_method,failed_over from gv$session where username in ('SYSTEM','SYS')
2*
INST_ID USERNAME FAILOVER_TYPE FAILOVER_M FAI
---------- ------------------------------ ------------- ---------- ---
2 SYS NONE NONE NO
2 SYS NONE NONE NO
2 SYS NONE NONE NO
2 SYS NONE NONE NO
2 SYS NONE NONE NO
2 SYS NONE NONE NO
1 SYS NONE NONE NO
1 SYS NONE NONE NO
1 SYS NONE NONE NO
1 SYSTEM SELECT BASIC NO
10 rows selected.
SQL>
可知目前system用戶已經具備failover功能。
注意：在配置client-side TAF的時候尤其注意參數的設置位置，否則無法實現failover。
其實在11G中scan功能也實現了負載均衡的作用，它是從dns解析中的三個地址輪詢負載的分配給scan listener進而采去和本地listener進行通信。
另外實現TAF的方式為server-side TAF。說白了，就是通過服務端設置service來實現，先比client-side TAF有很多簡便的方式。
eg：
增加服務名rac1和rac2：
oracle@rac-two ~]$ srvctl add service -d Rac -s rac1 -r Rac1 -a Rac2 -P basic -y automatic -e select -m basic -z 5 -w 120 [oracle@rac-two ~]$ srvctl add service -d Rac -s rac2 -r Rac2 -a Rac1 -P basic -y automatic -e select -m basic -z 5 -w 120
查看服務名狀態
[oracle@rac-two ~]$ srvctl status service -d RAc Service rac1 is not running. Service rac2 is not running.
啟動服務資源：
[oracle@rac-two ~]$ srvctl start service -d Rac [oracle@rac-two ~]$ srvctl status service -d Rac Service rac1 is running on instance(s) Rac1 Service rac2 is running on instance(s) Rac2
查看配置信息：
[oracle@rac-two ~]$ srvctl config service -d Rac Service name: rac1 Service is enabled Server pool: Rac_rac1 Cardinality: 1 Disconnect: false Service role: PRIMARY Management policy: AUTOMATIC DTP transaction: false AQ HA notifications: false Failover type: SELECT Failover method: BASIC TAF failover retries: 5 TAF failover delay: 120 Connection Load Balancing Goal: LONG Runtime Load Balancing Goal: NONE TAF policy specification: BASIC Edition: Preferred instances: Rac1 Available instances: Rac2 Service name: rac2 Service is enabled Server pool: Rac_rac2 Cardinality: 1 Disconnect: false Service role: PRIMARY Management policy: AUTOMATIC DTP transaction: false AQ HA notifications: false Failover type: SELECT Failover method: BASIC TAF failover retries: 5 TAF failover delay: 120 Connection Load Balancing Goal: LONG Runtime Load Balancing Goal: NONE TAF policy specification: BASIC Edition: Preferred instances: Rac2 Available instances: Rac1 [oracle@rac-two ~]$
注意這個時候，實例Rac1已經注冊了rac1服務，且主要實例為Rac1備用實例為Rac2，實例Rac2注冊了rac2服務，且主要實例為Rac2備用實例為Rac1；
本地監聽只會注冊本地服務名，scan監聽將注冊所有的監聽服務名。
驗證：
首先明確客戶端配置：
RAC =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = rac-two-cluster-scan.grid.example.com)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = Rac2)
)
)
登錄數據庫查看會話信息如下：
會話一使用system用戶登錄數據庫：
用戶沒有登錄之前狀態：
[oracle@rac-one ~]$ sqlplus / as sysdba SQL*Plus: Release 11.2.0.4.0 Production on Wed Mar 19 20:59:56 2014 Copyright (c) 1982, 2013, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP, Data Mining and Real Application Testing options SQL> col username for a20 SQL> set linesize 200 SQL> select inst_id,username,failover_type,failover_method,failed_over from gv$session where username='SYSTEM'; no rows selected
登錄之後狀態：
SQL> r
1* select inst_id,username,failover_type,failover_method,failed_over from gv$session where username='SYSTEM'
INST_ID USERNAME FAILOVER_TYPE FAILOVER_M FAI
---------- -------------------- ------------- ---------- ---
2 SYSTEM SELECT BASIC NO
2 SYSTEM SELECT BASIC NO
SQL>
這個時候關閉該節點，且在客戶端執行select * from dba_objects;語句，
查看節點二 用戶會話狀態。
SQL> r
1* select inst_id,username,failover_type,failover_method,failed_over from gv$session where username='SYSTEM'
INST_ID USERNAME FAILOVER_TYPE FAILOVER_M FAI
---------- -------------------- ------------- ---------- ---
1 SYSTEM SELECT BASIC YES
SQL>
可以看到用戶只在幾秒中停頓後繼續完成了select操作，且failed_over狀態為yes，證明failover已經生效。
查看狀態信息如下：
c[grid@rac-two ~]$ crsctl status res -t
--------------------------------------------------------------------------------
NAME TARGET STATE SERVER STATE_DETAILS
--------------------------------------------------------------------------------
Local Resources
--------------------------------------------------------------------------------
ora.DATADG.dg
ONLINE ONLINE rac-two
ora.GIDG.dg
ONLINE ONLINE rac-two
ora.LISTENER.lsnr
ONLINE ONLINE rac-two
ora.asm
ONLINE ONLINE rac-two Started
ora.gsd
OFFLINE OFFLINE rac-two
ora.net1.network
ONLINE ONLINE rac-two
ora.ons
ONLINE ONLINE rac-two
ora.registry.acfs
ONLINE ONLINE rac-two
--------------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------------
ora.LISTENER_SCAN1.lsnr
1 ONLINE ONLINE rac-two
ora.LISTENER_SCAN2.lsnr
1 ONLINE ONLINE rac-two
ora.LISTENER_SCAN3.lsnr
1 ONLINE ONLINE rac-two
ora.cvu
1 ONLINE ONLINE rac-two
ora.oc4j
1 ONLINE ONLINE rac-two
ora.rac-one.vip
1 ONLINE INTERMEDIATE rac-two FAILED OVER
ora.rac-two.vip
1 ONLINE ONLINE rac-two
ora.rac.db
1 ONLINE ONLINE rac-two Open
2 ONLINE OFFLINE Instance Shutdown
ora.rac.rac1.svc
1 ONLINE ONLINE rac-two
ora.rac.rac2.svc
1 ONLINE ONLINE rac-two
ora.scan1.vip
1 ONLINE ONLINE rac-two
ora.scan2.vip
1 ONLINE ONLINE rac-two
ora.scan3.vip
1 ONLINE ONLINE rac-two
[grid@rac-two ~]$
可知目前ora.ora-one.vip已經failed over，且ora.rac.rac1.svc運行到了rac-two中。
重啟節點後查看資源如下：
[grid@rac-one ~]$ crsctl status res -t
--------------------------------------------------------------------------------
NAME TARGET STATE SERVER STATE_DETAILS
--------------------------------------------------------------------------------
Local Resources
--------------------------------------------------------------------------------
ora.DATADG.dg
ONLINE ONLINE rac-one
ONLINE ONLINE rac-two
ora.GIDG.dg
ONLINE ONLINE rac-one
ONLINE ONLINE rac-two
ora.LISTENER.lsnr
ONLINE OFFLINE rac-one
ONLINE ONLINE rac-two
ora.asm
ONLINE ONLINE rac-one Started
ONLINE ONLINE rac-two Started
ora.gsd
OFFLINE OFFLINE rac-one
OFFLINE OFFLINE rac-two
ora.net1.network
ONLINE ONLINE rac-one
ONLINE ONLINE rac-two
ora.ons
ONLINE OFFLINE rac-one STARTING
ONLINE ONLINE rac-two
ora.registry.acfs
ONLINE ONLINE rac-one
ONLINE ONLINE rac-two
--------------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------------
ora.LISTENER_SCAN1.lsnr
1 ONLINE ONLINE rac-two STOPPING
ora.LISTENER_SCAN2.lsnr
1 ONLINE ONLINE rac-two
ora.LISTENER_SCAN3.lsnr
1 ONLINE ONLINE rac-two
ora.cvu
1 ONLINE ONLINE rac-two
ora.oc4j
1 ONLINE ONLINE rac-two
ora.rac-one.vip
1 ONLINE INTERMEDIATE rac-two FAILED OVER,STOPPING
ora.rac-two.vip
1 ONLINE ONLINE rac-two
ora.rac.db
1 ONLINE ONLINE rac-two Open
2 ONLINE OFFLINE Instance Shutdown
ora.rac.rac1.svc
1 ONLINE ONLINE rac-two
ora.rac.rac2.svc
1 ONLINE ONLINE rac-two
ora.scan1.vip
1 ONLINE ONLINE rac-two
ora.scan2.vip
1 ONLINE ONLINE rac-two
ora.scan3.vip
1 ONLINE ONLINE rac-two
[grid@rac-one ~]$
[grid@rac-one ~]$ crsctl status res -t
--------------------------------------------------------------------------------
NAME TARGET STATE SERVER STATE_DETAILS
--------------------------------------------------------------------------------
Local Resources
--------------------------------------------------------------------------------
ora.DATADG.dg
ONLINE ONLINE rac-one
ONLINE ONLINE rac-two
ora.GIDG.dg
ONLINE ONLINE rac-one
ONLINE ONLINE rac-two
ora.LISTENER.lsnr
ONLINE ONLINE rac-one
ONLINE ONLINE rac-two
ora.asm
ONLINE ONLINE rac-one Started
ONLINE ONLINE rac-two Started
ora.gsd
OFFLINE OFFLINE rac-one
OFFLINE OFFLINE rac-two
ora.net1.network
ONLINE ONLINE rac-one
ONLINE ONLINE rac-two
ora.ons
ONLINE ONLINE rac-one
ONLINE ONLINE rac-two
ora.registry.acfs
ONLINE ONLINE rac-one
ONLINE ONLINE rac-two
--------------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------------
ora.LISTENER_SCAN1.lsnr
1 ONLINE ONLINE rac-one
ora.LISTENER_SCAN2.lsnr
1 ONLINE ONLINE rac-two
ora.LISTENER_SCAN3.lsnr
1 ONLINE ONLINE rac-two
ora.cvu
1 ONLINE ONLINE rac-two
ora.oc4j
1 ONLINE ONLINE rac-two
ora.rac-one.vip
1 ONLINE ONLINE rac-one
ora.rac-two.vip
1 ONLINE ONLINE rac-two
ora.rac.db
1 ONLINE ONLINE rac-two Open
2 ONLINE ONLINE rac-one Open
ora.rac.rac1.svc
1 ONLINE ONLINE rac-two
ora.rac.rac2.svc
1 ONLINE ONLINE rac-two
ora.scan1.vip
1 ONLINE ONLINE rac-one
ora.scan2.vip
1 ONLINE ONLINE rac-two
ora.scan3.vip
1 ONLINE ONLINE rac-two
[grid@rac-one ~]$
如果當Rac1失效（節點關閉），那麼select將再次移動到Rac2上來
SQL> r
1* select inst_id,username,failover_type,failover_method,failed_over from gv$session where username='SYSTEM'
INST_ID USERNAME FAILOVER_TYPE FAILOVER_M FAI
---------- ------------------------------ ------------- ---------- ---
2 SYSTEM SELECT BASIC YES
到了11G R2 使用scan和server-side TAF是最佳選擇。
That’s all！！！！！
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++Rhys↖(^ω^)↗Amy+++++++++++++++++++++++++++
