Client connections can be either high availability connections or non-high-availability connections. In either case, client connections require:
Adequate values for the retry and timeout options in the interfaces file. When you determine these values, allow for failover delays, such as starting Adaptive Server on the secondary node, recovery time, and for multiple node failures. The Adaptive Server resource group tries to fail over until it finds a secondary node that can successfully host the resource group.
The logical host name be accessible from the client machine.
non-high-availability connections do not include neither the hafailover entry in the interfaces file nor the CS_HAFAILOVER property set in the client connection. When non-high-availability connections are lost, clients must reconnect to the Adaptive Server after failure. To reestablish the connections, clients must retry enough times, or wait long enough between retries, until fail over completes and Adaptive Server is running on the secondary node.
To reconnect to the server, clients can use the retry and timeout options in the interfaces file or the corresponding connection properties. In the following interfaces file example, the retry count is 10 and the timeout delay between each retry is 20 seconds:
MONEY 10 20 master tcp ether loghost 4010 query tcp ether loghost 4010
High availability connections are made with:
The CS_HAFAILOVER property set at the connection or context level (equivalent to the -Q option of isql).
The hafailover entry in the interfaces file, which must point to the Adaptive Server entry to be contacted in case of fail over.
In an active-passive configuration, clients must self-reference the hafailover entry because they reconnect to the same Adaptive Server after fail over. That is, they must set the same server name as the hafailover server in the interfaces file because the same Adaptive Server is restarted on the secondary node.
For example, the Adaptive Server entry in the example above can be self- referenced as:
MONEY 10 20 master tli tcp loghost 4010 query tli tcp loghost 4010 hafailover MONEY
For more information about configuring client connections with the failover property, see Appendix C, “Open Client Functionality in a Failover Configuration.”
| Copyright © 2005. Sybase Inc. All rights reserved. |
|
|
