You can use the solidDB HotStandby (HSB) component to make SMA servers highly available. For information about SMA, see Shared Memory Access (SMA).
When you use SMA servers in an HSB system, there can be one or more SMA applications on each server. The application connection to the database can be configured as a regular SMA connection (SMA Basic Connectivity) or as a Transparent Connectivity SMA connection (SMA TC). With both connectivity types, the application on the primary server uses an SMA connection to execute reads and writes locally, and the application on the secondary server uses an SMA connection to execute reads locally. Additionally, with an SMA TC connection, write transactions from the application on the secondary server can be executed on the primary server by using a network connection. Furthermore, if the load balancing option is enabled with the SMA TC connection, the applications can operate in an active-active manner; on each server, the full functionality of database access is available.
With SMA TC, the application on each server must be able to connect to the local server with an SMA connection and to the remote server with a network-based connection.
Failover and switchover handling
▪ The connection handle is maintained during switchovers and failovers as long as one of the servers is in the PRIMARY ACTIVE, PRIMARY ALONE, or STANDALONE state.
▪ If the SMA server fails, the application might also fail. To ensure high availability in such a failure scenario, your system must include an application-level failover mechanism that moves the service offered by the application from the failed application instance to another application instance.
