Adaptive Servers configured as companions in a high availability system have different resource requirements than Adaptive Servers that function individually. These differences exist because the secondary companion must process all the work during fail over. This is true even if the companions are set up asymmetrically. Consequently, an Adaptive Server in a high availability system has higher resource requirements than if it is a single server. For more information, see “Single-system presentation”.
The following are some of the resource requirements that you should consider when you configure Adaptive Server as a cluster companion (your site will have its own set of resource requirements that must be addressed).
Logins, roles, and databases – you must set the number of logins, roles, and databases for the cluster equal to the total number for one Adaptive Server.
number of user connections – each companion must be configured for the total number of user connections required for the system.
number of open databases – each companion must be configured for the total number of open databases required for the system.
srids – each companion must be configured for the total number of srids required for the system.
number of devices – each Adaptive Server must be configured for the total number of devices used by the cluster, not the number of devices used individually. That is, if one companion uses 14 devices and the second uses 23, each Adaptive Server must be configured with 37 as the number of devices.
sp_configure option number of open databases – on an Adaptive Server configured for failover, the number of open databases is reduced by two to ensure successful failover. That is, if you currently have the number of open databases as ten, you can open only eight databases.
sp_configure option number of user connections – on an Adaptive Server configured for failover, the number of user connections is reduced by two to ensure successful failover. That is, if the number of user connections is 50, you can use only 48 user connections.
Client applications that connect to companion servers must relink their libraries with the libraries included with failover software. See “CTLIB application changes” for more information about using Open Client with failover.
