High availability strategies

HCL Informix® can be configured to maximize availability in various business situations.

Goal Strategy Advantages Potential disadvantages
Protect system from server failure Use a secondary server that shares disk space with the primary server. (shared-disk secondary server)
  • Very high availability. This secondary server has access to the same data as the primary server. If the primary server fails, the secondary server can take over quickly.
  • The database is always in sync because this secondary server has access to the same data as the primary server.
  • No requirement to change applications. Client connections to primary or secondary server are automatically switched in the event of server failure.
  • This secondary server on the same computer as the primary server.
  • No data redundancy. This secondary server does not maintain a copy of the data. (Use SAN devices for disk storage.)
  • Primary and secondary servers require the same hardware, operating system, and version of the database server product.
  • Secondary server hardware must be able to handle the same load as the primary server. If the secondary server is too small, it might affect the performance of the primary.
Protection from site failure
  • Use a secondary server that maintains a copy of the database server and the data. (high availability data replication server)
  • (Can also use RSS and ER)
  • Very high availability. Applications can access this server quickly if they cannot connect to a primary server.
  • Data is replicated synchronously.
  • Increased scalability
  • No requirement to change applications
  • Local to the primary
  • Requires an exact replica of the data (including table and database schemas).
  • Primary and secondary servers require the same hardware, operating system, and version of the database server product.
Multilevel site failure protection
  • Use a secondary server that is geographically distant from the primary server and that is updated asynchronously from the primary server. (remote stand-alone secondary server)
  • (Can also use ER)
  • Very high availability. Applications can access this server quickly if they cannot connect to a primary server.
  • Data is replicated asynchronously.
  • Increased scalability
  • No requirement to change applications
 
Geographically dispersed processing with site failure protection ER and HDR ER and backup for ER Multiple connection managers required

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