Transparent Application Failover - TAF
TAF offers Run-Time failover capability to the client connections. For example, if the client connects to the instance 1 and if that instance crashes, then this connection will be automatically and transparently failed over to the one of the other instance. After the failover it can resume any SELECT query that was in process or it can only fail over the SESSION and do not replay the SELECT query. These are called two types of TAF i.e. SESSION and SELECT.There are also two methods of TAF, BASIC and PRECONNECT. In the BASIC method, the client first makes only one connection to the database, if that connection fails then it initiates another connection as part of failover operation. In the case of PRECONNECT method, the client makes two connection at the initial stages itself. If the first connection crashes, then it immediately starts using the second connection. It saves connection establishment time during failover.TAF can be configured at the client side in tnsnames.ora or at the server side with the srvctlcommand. You actually create a service which is TAF enabled with the srvctlcommand.
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TAF offers Run-Time failover capability to the client connections. For example, if the client connects to the instance 1 and if that instance crashes, then this connection will be automatically and transparently failed over to the one of the other instance. After the failover it can resume any SELECT query that was in process or it can only fail over the SESSION and do not replay the SELECT query. These are called two types of TAF i.e. SESSION and SELECT.There are also two methods of TAF, BASIC and PRECONNECT. In the BASIC method, the client first makes only one connection to the database, if that connection fails then it initiates another connection as part of failover operation. In the case of PRECONNECT method, the client makes two connection at the initial stages itself. If the first connection crashes, then it immediately starts using the second connection. It saves connection establishment time during failover.TAF can be configured at the client side in tnsnames.ora or at the server side with the srvctlcommand. You actually create a service which is TAF enabled with the srvctlcommand.
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