客户端负载均衡及透明应用切换(TAF)
这是客户端的一种功能,要在客户端的tnsnames.ora中设置本地服务命名相应的参数(LOAD_BALANCE=ON和FAILOVER=ON、FAILOVER_MODE参数)来启用客户端负载均衡和TAF功能。客户端负载均衡并不衡量RAC节点CPU的使用率,它只是随机的连接一个节点的监听。由于是随机连接,所以大体上做到连接数的负载均衡。在RAC环境中设置tnsnames.ora时,应使用SERVICE_NAME
而不要使用SID,但是在使用RMAN进行备份和恢复时必须使用SID而不能使用SERVICE_NAME
RAC双主模式时,客户端可以只使用一个本地服务命名(无预连接功能),或者使用两个本地服务命名(有预连接功能)
具有客户端负载均衡及透明应用切换无预连接的tnsnames配置
RAC9I =
(DEscrīptION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = tcp)(HOST = rac9iaw)(PORT = 1521))
(ADDRESS = (PROTOCOL = tcp)(HOST = rac9ibw)(PORT = 1521))
(LOAD_BALANCE = ON)
(FAILOVER = ON)
)
(CONNECT_DATA =
(SERVICE_NAME = rac9i.xyf)
(FAILOVER_MODE =
(TYPE = select)
(METHOD = basic)
(RETRIES = 10)
(DELAY = 1)
)
)
)
无客户端负载均衡有透明应用切换且有预连接的tnsnames配置
RAC9I1 =
(DEscrīptION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = tcp)(HOST = rac9iaw)(PORT = 1521))
(LOAD_BALANCE = OFF)
(FAILOVER = ON)
)
(CONNECT_DATA =
(SERVICE_NAME = rac9i.xyf)
(INSTANCE_NAME = rac9i1)
(FAILOVER_MODE =
(BACKUP=RAC9I2)
(TYPE = select)
(METHOD = preconnect)
)
)
)
RAC9I2 =
(DEscrīptION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = tcp)(HOST = rac9ibw)(PORT = 1521))
(LOAD_BALANCE = OFF)
(FAILOVER = ON)
)
(CONNECT_DATA =
(SERVICE_NAME = rac9i.xyf)
(INSTANCE_NAME = rac9i2)
(FAILOVER_MODE =
(BACKUP=RAC9I1)
(TYPE = select)
(METHOD = preconnect)
)
)
)
参数的含义:
LOAD_BALANE FAILOVER
ON ON 客户端新建连接随机尝试ADDRESS_LIST中的监听,直到连接到一个可用监听,或者连完列表中的所有监听,如没有一个监听可用,则返回错误信息
ON OFF 客户端新建连接随机尝试ADDRESS_LIST中的任一监听,无论这个监听是否可用,如不可用直接返回错误。
OFF ON 客户端新建连接按顺序尝试ADDRESS_LIST中的监听,直到连接到一个可用监听,或者连完列表中的所有监听如没有一个监听可用,则返回错误信息
OFF OFF 客户端新建连接仅连接ADDRESS_LIST中第一个监听,无论这个监听是否可用,如不可用直接返回错误。
对于已有连接的失败切换,首先要求FAILOVER = ON,并且设置了FAILOVER_MODE
FAILOVER_MODE的子参数含义:
TYPE:1)session---如果用户连接丢失,将创建一个新的会话连接到备用节点,用户的所有未提交的操作必须回滚,然后再次执行,SELECT操作也被中止.
2)select---如果用户连接丢失,将使用游标和之前的快照继续执行SELECT操作,叫做SQL接管,SQL接管能够无缝接管理的事务类型只有SELECT语句.其它的操作也必须要回滚然后再次执行.
3)none---客户端默认值,禁止SQL接管功能,主要用于测试的目地,在实际应用中TYPE应指定为session或者select
METHOD:1)basic---仅仅在FAILOVER发生时才连接备用节点
2)preconnect---在用户连接到主节点时同时也在备用节点产生一个连接会话,设置预连接模式,能够快速接管SQL
RETRIES:当前节点失败后,失败切换功能会尝试连接备用节点,这个值确定了尝试的次数,如果仅DELAY被指定,RETRIES默认为5
DELAY:两次尝试之间等待的秒数,如果仅指定RETRIES,DELAY默认为1秒
BACKUP:指定另外一个用于备份连接的网络服务名,当RAC设置为主次模式时,使用此参数,并且METHOD应该设为preconnect
RAC设置为主次模式时的tnsnames配置
无客户端负载均衡(主次模式就不要客户端负载均衡了),有透明应用切换且有预连接的tnsnames配置
RAC9I1 =
(DEscrīptION =
(ADDRESS = (PROTOCOL = tcp)(HOST = rac9iaw)(PORT = 1521))
(ADDRESS = (PROTOCOL = tcp)(HOST = rac9ibw)(PORT = 1521))
(LOAD_BALANCE = OFF)
(FAILOVER = ON)
(CONNECT_DATA =
(SERVICE_NAME = rac9i.xyf)
(INSTANCE_ROLE = PRIMARY)
(INSTANCE_NAME = rac9i1)
(FAILOVER_MODE =
(BACKUP=RAC9I2)
(TYPE = select)
(METHOD = preconnect)
)
)
)
RAC9I2 =
(DEscrīptION =
(ADDRESS = (PROTOCOL = tcp)(HOST = rac9ibw)(PORT = 1521))
(ADDRESS = (PROTOCOL = tcp)(HOST = rac9iaw)(PORT = 1521))
(LOAD_BALANCE = OFF)
(FAILOVER = ON)
(CONNECT_DATA =
(SERVICE_NAME = rac9i.xyf)
(INSTANCE_ROLE = SECONDARY)
(INSTANCE_NAME = rac9i2)
(FAILOVER_MODE =
(BACKUP=RAC9I1)
(TYPE = select)
(METHOD = preconnect)
)
)
)
也可以设置为有透明应用切换但无预连接的模式,只要把上面的设置中的METHOD设置为basic。
与双主模式时的配置相比,多了INSTANCE_ROLE这样一个参数,当这个参数为SECONDARY时,
这个本地服务命名不直接接收连接,只在主节点失败后才会接收连接。不直接接收连接,并不是指在客户端不能连通这个服务命名,只不过这个连接会被路由到主节点,次要次点并不真正有连接连上去。
来源:http://blog.csdn.net/qyq88888/article/details/4475328
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Q:有一段 RAC的配置(3节点rac)
###### RAC的配置(3节点rac) ###############################
ORALOCAL =
(DESCRIPTION =
(load_balance = yes)
(failover = on)
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.1)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.2)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.3)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = oralocal)
(SERVER = DEDICATED)
(failover_mode=(type=select)(method=basic)(retries=20)(delay=20))
)
)
ORALOCAL_NODE1 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.1)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = oralocal)
(INSTANCE_NAME = oralocal_node1)
)
)
ORALOCAL_NODE2=
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.2)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = oralocal)
(INSTANCE_NAME = oralocal_node2)
)
)
ORALOCAL_NODE3 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.3)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = oralocal)
(INSTANCE_NAME = oralocal_node3)
)
)
哪位帮我解译一下里面的句子都是什么意思!
A:如果楼主需要详细资料建议去搜一下TAF.
另外,ORALOCAL_NODE1,ORALOCAL_NODE2,ORALOCAL_NODE3在他这里没有作用,只是提供每个节点的连接服务,你如果只想连接某个单节点,可以配置.但是如果TAF中使用了backup的话,必须提供一个backup服务.他这里没用,所以不需要.