11gR2 RAC connection management
对于RAC来说，当Oracle Instance失败的，应用有几种高可用技术来保证可用性，这些技术对客户端来说都是透明的，客户端可能感知不到instance failure。
一.Transparent Application Failover (TAF)
二.Fast Connection Failover (FCF).
当一个节点failure的时候，TAF允许数据库session使用OCI libraries进行fail over到其他存活的一个节点。但是如果应用使用JDBC thin driver则不能使用TAF。
Failover Modes：
Session failover
Select failover
None(default)
1.select mode允许query重新在新的节点执行，并且丢弃已经fetch的行，继续返回结果给客户端。
2.none mode显式的声明不使用TAF
3.TAF不能够恢复任何DML事务，事务将在另一个节点回滚。
Failover Methods:
Basic
Preconnect
1.Basic选项意味着客户端在实例失败后重新建立新的连接，这个method可能导致节点失败时，另一节点的性能下降，因为有很多的session将要重新连接到幸存的节点。
2.客户端产生一个preconnected session作为备份，在实例失败时加速failover。
TAF是client-side feature，我们需要配置它在客户端Tnsnames.ora或者server端通过service来实现
1，客户端实现
instance failure failover。
FCF支持的客户端驱动：
Java Database Connection Driver (JDBC)
Oracle Universal Connection Pool UCP
Clients using the Oracle Call Interface
Oracle Data Providers for .Net
在11R2(11.2.0.1)中当设置了db_domain参数，FCF将会失效，bug:8779597
11gR2中默认配置客户端通过如下：
那么客户端的tnsnames.ora来做如下配置：
1.Client Side Load Balance
当客户端通过SCAN连接11gR2 RAC，load balance发生在连接阶段(可以通过sqlnet的trace来确认)，Scan name被解析成最多三个不同的IP，
客户端随机的选择一个IP去连接。
对于非11gR2 client，是不能使用SCAN的好处，因为它不能处理DNS解析的SCAN ip，所以，在address_list里，它将
尝试用第一个address去连接，不会使用其他的地址，那么如果这个ip地址不能被scan listener监听或者ip本事存在问题，连接就会失败。
使用静态的SCAN IP(未使用GNS)的tnsnames.ora的条目如下：
关于rac连接管理的详细文档，崔华写过一篇很详细，可以参阅：
一.Transparent Application Failover (TAF)
二.Fast Connection Failover (FCF).
当一个节点failure的时候，TAF允许数据库session使用OCI libraries进行fail over到其他存活的一个节点。但是如果应用使用JDBC thin driver则不能使用TAF。
Failover Modes：
Session failover
Select failover
None(default)
1.select mode允许query重新在新的节点执行，并且丢弃已经fetch的行，继续返回结果给客户端。
2.none mode显式的声明不使用TAF
3.TAF不能够恢复任何DML事务，事务将在另一个节点回滚。
Failover Methods:
Basic
Preconnect
1.Basic选项意味着客户端在实例失败后重新建立新的连接，这个method可能导致节点失败时，另一节点的性能下降，因为有很多的session将要重新连接到幸存的节点。
2.客户端产生一个preconnected session作为备份，在实例失败时加速failover。
TAF是client-side feature，我们需要配置它在客户端Tnsnames.ora或者server端通过service来实现
1，客户端实现
RAC中在tnsnames.ora里面典型配置如下：
LEO1 =
(DESCRIPTION_LIST =
(LOAD_BALANCE = off)
(FAILOVER = on)
(DESCRIPTION =
(ADDRESS_LIST =
(LOAD_BALANCE=OFF)
(FAILOVER=ON)
(ADDRESS = (PROTOCOL = TCP)(HOST = node1.chinamobile.com)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = leo)
(INSTANCE_NAME = leo1)
(FAILOVER_MODE=(TYPE=session)(METHOD=basic)(RETRIES=4)(DELAY=1))
)
)
(DESCRIPTION =
(ADDRESS_LIST =
(LOAD_BALANCE=OFF)
(FAILOVER=ON)
(ADDRESS = (PROTOCOL = TCP)(HOST = node2.chinamobile.com)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = leo)
(INSTANCE_NAME = leo2)
(FAILOVER_MODE=(TYPE=session)(METHOD=basic)(RETRIES=4)(DELAY=1))
)
)
)2，server端实现
srvctl add service -d leo -s cmcc -q TRUE -P BASIC -e SESSION -z 4 -w 5 具体使用参数如下：
Usage: srvctl add service -d <db_unique_name> -s <service_name> {-r "<preferred_list>" [-a "<available_list>"] [-P {BASIC | NONE | PRECONNECT}]
| -g <pool_name> [-c {UNIFORM | SINGLETON}] } [-k <net_num>] [-l [PRIMARY][,PHYSICAL_STANDBY][,LOGICAL_STANDBY][,SNAPSHOT_STANDBY]]
[-y {AUTOMATIC | MANUAL}] [-q {TRUE|FALSE}] [-x {TRUE|FALSE}] [-j {SHORT|LONG}] [-B {NONE|SERVICE_TIME|THROUGHPUT}]
[-e {NONE|SESSION|SELECT}] [-m {NONE|BASIC}] [-z <failover_retries>] [-w <failover_delay>] [-t <edition>] [-f]
-d <db_unique_name> Unique name for the database
-s <service> Service name
-r "<preferred_list>" Comma separated list of preferred instances
-a "<available_list>" Comma separated list of available instances
-g <pool_name> Server pool name
-c {UNIFORM | SINGLETON} Service runs on every active server in the server pool hosting this service (UNIFORM) or just one server (SINGLETON)
-k <net_num> network number (default number is 1)
-P {NONE | BASIC | PRECONNECT} TAF policy specification
-l <role> Role of the service (primary, physical_standby, logical_standby, snapshot_standby)
-y <policy> Management policy for the service (AUTOMATIC or MANUAL)
-e <Failover type> Failover type (NONE, SESSION, or SELECT)
-m <Failover method> Failover method (NONE or BASIC)
-w <integer> Failover delay
-z <integer> Failover retries
-t <edition> Edition (or "" for empty edition value)
-j <clb_goal> Connection Load Balancing Goal (SHORT or LONG). Default is LONG.
-B <Runtime Load Balancing Goal> Runtime Load Balancing Goal (SERVICE_TIME, THROUGHPUT, or NONE)
-x <Distributed Transaction Processing> Distributed Transaction Processing (TRUE or FALSE)
-q <AQ HA notifications> AQ HA notifications (TRUE or FALSE)
Usage: srvctl add service -d <db_unique_name> -s <service_name> -u {-r "<new_pref_inst>" | -a "<new_avail_inst>"} [-f]
-d <db_unique_name> Unique name for the database
-s <service> Service name
-u Add a new instance to service configuration
-r <new_pref_inst> Name of new preferred instance
-a <new_avail_inst> Name of new available instance
-f Force the add operation even though a listener is not configured for a network
-h Print usage
Fast Connection Failover and Fast Application Notification
FAN是一种消息发布机制，在instance up/down发布消息到客户端，来进行群集的重新配置，FCF是通过FAN来透明的进行instance failure failover。
FCF支持的客户端驱动：
Java Database Connection Driver (JDBC)
Oracle Universal Connection Pool UCP
Clients using the Oracle Call Interface
Oracle Data Providers for .Net
在11R2(11.2.0.1)中当设置了db_domain参数，FCF将会失效，bug:8779597
下面看看11gR2的情况：
11gR2出现了scan，相应的listener配置也有所变化：
$GRID_HOME/network/admin目录下：
-rw-r--r-- 1 grid oinstall 695 May 1 16:43 listener.ora
-rw-r--r-- 1 grid oinstall 369 May 1 16:43 endpoints_listener.ora
[grid@node2 admin]$ cat listener.ora
LISTENER2=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER2)))) # line added by Agent
# listener.ora.node2 Network Configuration File: /u01/app/11.2.0.3/grid/network/admin/listener.ora.node2
# Generated by Oracle configuration tools.
ENABLE_GLOBAL_DYNAMIC_ENDPOINT_LISTENER_SCAN1 = ON
ENABLE_GLOBAL_DYNAMIC_ENDPOINT_LISTENER1 = ON
LISTENER =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = LISTENER))
)
)
ENABLE_GLOBAL_DYNAMIC_ENDPOINT_LISTENER = ON
LISTENER_SCAN1 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = LISTENER_SCAN1))
)
)
ENABLE_GLOBAL_DYNAMIC_ENDPOINT_LISTENER2=ON # line added by Agent
[grid@node2 admin]$ cat endpoints_listener.ora
LISTENER2_NODE2=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=node2-vip)(PORT=1522))
(ADDRESS=(PROTOCOL=TCP)(HOST=10.180.69.103)(PORT=1522)(IP=FIRST)))) # line added by Agent
LISTENER_NODE2=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=node2-vip)(PORT=1521))
(ADDRESS=(PROTOCOL=TCP)(HOST=10.180.69.103)(PORT=1521)(IP=FIRST)))) # line added by Agent
查看scan ip的配置和状态：
[grid@node2 admin]$ srvctl config scan
SCAN name: scanip, Network: 1/10.180.69.0/255.255.255.0/eth0
SCAN VIP name: scan1, IP: /scanip/10.180.69.105
[grid@node2 admin]$ srvctl status scan
SCAN VIP scan1 is enabled
SCAN VIP scan1 is running on node node2
[grid@node2 admin]$ srvctl status scan_listener
SCAN Listener LISTENER_SCAN1 is enabled
SCAN listener LISTENER_SCAN1 is running on node node2
验证实例注册：
grid@node2 admin]$ lsnrctl status listener_scan1 LSNRCTL for Linux: Version 11.2.0.3.0 - Production on 09-JUN-2012 15:04:39 Copyright (c) 1991, 2011, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_SCAN1))) STATUS of the LISTENER ------------------------ Alias LISTENER_SCAN1 Version TNSLSNR for Linux: Version 11.2.0.3.0 - Production Start Date 07-JUN-2012 19:30:34 Uptime 1 days 19 hr. 34 min. 5 sec Trace Level support Security ON: Local OS Authentication SNMP OFF Listener Parameter File /u01/app/11.2.0.3/grid/network/admin/listener.ora Listener Log File /u01/app/11.2.0.3/grid/log/diag/tnslsnr/node2/listener_scan1/alert/log.xml Listener Trace File /u01/app/11.2.0.3/grid/log/diag/tnslsnr/node2/listener_scan1/trace/ora_6446_3050497728.trc Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN1))) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=10.180.69.105)(PORT=1521))) Services Summary... Service "leo" has 2 instance(s). Instance "leo1", status READY, has 2 handler(s) for this service... Instance "leo2", status READY, has 2 handler(s) for this service... Service "leoXDB" has 1 instance(s). Instance "leo1", status READY, has 1 handler(s) for this service... Instance "leo2", status READY, has 1 handler(s) for this service... The command completed successfully监听listener_scan1运行在node2，两个实例是被注册的，群集内的每个节点实例通过remote listener来注册自身。
SQL> show parameter list
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
local_listener string (DESCRIPTION=(ADDRESS_LIST=(AD
DRESS=(PROTOCOL=TCP)(HOST=10.1
80.69.104)(PORT=1521))(ADDRESS
=(PROTOCOL=TCP)(HOST=10.180.69
.104)(PORT=1522))))
remote_listener string scanip:1521
这里因为我添加另外一个本地监听，所以local_listener有两个。11gR2中默认配置客户端通过如下：
LEO =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = scanip)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = leo)
)
)
现在我们来看看11gR2的TAF,之前提到TAF可以在客户端的tnsnames.ora里配置，也可以在server端通过添加service来配置。
那么客户端的tnsnames.ora来做如下配置：
LEO_TAF =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = scanip)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = leo)
(FAILOVER_MODE=
(TYPE=session)
(METHOD=basic))))
可以通过如下查询来验证客户端TAF:
SELECT MACHINE, FAILOVER_TYPE, FAILOVER_METHOD, FAILED_OVER, COUNT(*)
FROM V$SESSION
GROUP BY MACHINE, FAILOVER_TYPE, FAILOVER_METHOD, FAILED_OVER;
MACHINE FAILOVER_TYPE FAILOVER_M FAI COUNT(*)
-------------------- ------------- ---------- --- ----------
Thinkpad-leo SESSION BASIC NO 5
如果是Server端的，来看看配置的过程：
1.create service(Use Oracel Account) ./srvctl add service -d leo -s taf -q TRUE -r leo2 -P BASIC -e SESSION -z 4 -w 5 2.start service srvctl start service -d leo -s taf 3.check service srvctl config service -d leo Service name: taf Service is enabled Server pool: leo_taf Cardinality: 1 Disconnect: false Service role: PRIMARY Management policy: AUTOMATIC DTP transaction: false AQ HA notifications: true Failover type: SESSION Failover method: BASIC TAF failover retries: 4 TAF failover delay: 5 Connection Load Balancing Goal: LONG Runtime Load Balancing Goal: NONE TAF policy specification: BASIC Edition: Preferred instances: leo2 Available instances: leo1 srvctl status service -d leo Service taf is running on instance(s) leo24.查看信息
col failover_method format a11 heading 'METHOD'
col failover_type format a10 heading 'TYPE'
col failover_retries format 9999999 heading 'RETRIES'
col goal format a10
col clb_goal format a8
col AQ_HA_NOTIFICATIONS format a5 heading 'AQNOT'
select name, failover_method, failover_type, failover_retries,goal, clb_goal,aq_ha_notifications
from dba_services where service_id = 3;
NAME METHOD TYPE RETRIES GOAL CLB_GOAL AQNOT
--------------- ----------- ---------- -------- ---------- -------- -----
taf BASIC SESSION 4 LONG YES
5.查看监听
LSNRCTL> services
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_SCAN1)))
Services Summary...
Service "leo" has 1 instance(s).
Instance "leo2", status READY, has 2 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0 state:ready
REMOTE SERVER
(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.180.69.104)(PORT=1522)))
"DEDICATED" established:0 refused:0 state:ready
REMOTE SERVER
(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.180.69.104)(PORT=1521)))
Service "leoXDB" has 1 instance(s).
Instance "leo2", status READY, has 1 handler(s) for this service...
Handler(s):
"D000" established:0 refused:0 current:0 max:1022 state:ready
DISPATCHER <machine: node2, pid: 10911>
(ADDRESS=(PROTOCOL=tcp)(HOST=node2)(PORT=18689))
Service "taf" has 1 instance(s).
Instance "leo2", status READY, has 2 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0 state:ready
REMOTE SERVER
(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.180.69.104)(PORT=1522)))
"DEDICATED" established:0 refused:0 state:ready
REMOTE SERVER
(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=10.180.69.104)(PORT=1521)))
The command completed successfully
Load Balance：1.Client Side Load Balance
当客户端通过SCAN连接11gR2 RAC，load balance发生在连接阶段(可以通过sqlnet的trace来确认)，Scan name被解析成最多三个不同的IP，
客户端随机的选择一个IP去连接。
对于非11gR2 client，是不能使用SCAN的好处，因为它不能处理DNS解析的SCAN ip，所以，在address_list里，它将
尝试用第一个address去连接，不会使用其他的地址，那么如果这个ip地址不能被scan listener监听或者ip本事存在问题，连接就会失败。
使用静态的SCAN IP(未使用GNS)的tnsnames.ora的条目如下：
LEO_LB =
(DESCRIPTION =
(ADDRESS_LIST =
(LOAD_BALANCE=ON)
(FAILOVER=ON)
(ADDRESS = (PROTOCOL = TCP)(HOST = <scan-VIP1>)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = <scan-VIP2>)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = <scan-VIP3>)(PORT = 1521))
)
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = leo)
(FAILOVER_MODE=
(TYPE=session)
(METHOD=basic))))
10g对方式：
LEO =
(DESCRIPTION =
(LOAD_BALANCE = yes)
(ADDRESS = (PROTOCOL = TCP)(HOST = node1)
(PORT = 1522))
(ADDRESS = (PROTOCOL = TCP)(HOST = node2-vip)
(PORT = 1522))
(CONNECT_DATA =
(SERVICE_NAME = LEO)))
--JDBC--
url="jdbc:oracle:thin:@(DESCRIPTION=(LOAD_BALANCE=on)
(ADDRESS=(PROTOCOL=TCP)(HOST=node1-vip)(PORT=1521))
(ADDRESS=(PROTOCOL=TCP)(HOST=node2-vip)(PORT=1521))
(CONNECT_DATA=(SERVICE_NAME=LEO)))"
关于rac连接管理的详细文档，崔华写过一篇很详细，可以参阅：
http://www.oracle.com/technetwork/cn/articles/database-performance/oracle-rac-connection-mgmt-1650424-zhs.html
http://www.oracle.com/technetwork/database/clustering/overview/scan-129069.pdf