Login redirection occurs at login time when an instance tells a client to log in to another instance because of load considerations.
You do not need to perform any additional configuration for client redirection.
Login redirection is used by the Adaptive Server workload manager to send incoming connections to specific instances based on the logical cluster configuration and the cluster’s current workload.
If you attempt to connect to an instance that is down, behavior is the same as with a nonclustered Adaptive Server: the client tries all entries in the directory service of a given server until it can connect successfully. Because of this, your server entries in the directory service should contain connection information for all instances in the cluster.
This example includes the Adaptive Servers “ase1,” “ase2,” “ase3,” and “ase4,” on machines “blade1,” “blade2,” “blade3,” and “blade4,” running in the cluster “mycluster.”
ase1 query tcp ether blade1 19786 ase2 query tcp ether blade2 19786 ase3 query tcp ether blade3 19786 ase4 query tcp ether blade4 19786
mycluster query tcp ether blade1 19786 query tcp ether blade2 19786 query tcp ether blade3 19786 query tcp ether blade4 19786
For example, if a client connects to cluster “mycluster,” it first tries to connect to the “ase1” instance. If “ase1” is down, it tries the next entry in the interfaces file, “ase2”, and so on. After a successful connection, the workload manager may redirect the client to another instance based on workload rules.
Although instances are tried in the order specified in the interfaces file, it can take a considerable amount time for a connection attempt to fail when hosts or the network are unreachable or down. You can expedite the retry attempt by adding a login timeout to the connection information.
In the example above, if you specified a login timeout interval that is shorter than the default for the connecting client, the client could attempt to connect to instance “ase2” more quickly.
See the isql -l parameter description in the Adaptive Server Utility Guide and CS_LOGIN_TIMEOUT property for Client-Library Reference Manual.
