Adaptive Servers configured as companions in a high availability system have different resource requirements than Adaptive Servers that function individually. These different resource requirements exists because the secondary companion must process all the work during failover. This is true even if the companions are setup asymmetrically. Consequently, an Adaptive Server in a high availability system has higher resource requirements than it would have if it was 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 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.
The sp_configure option number of open databases on an Adaptive Server configured for Failover is reduced by two to ensure successful failover. That is, if you currently have the number of open databases set to 10, you will only be able to open eight databases.
The sp_configure option number of user connections on an Adaptive Server configured for Failover is reduced by two to ensure successful failover. That is, if you currently have the number of user connections set to 50, you will only be able to use 48 user connections.
