Posted: 20 Oct, 2011
Redundancy is used to increase the fault tolerance of a system by duplicating critical components and functions. Redundancy within Pipeline Application Systems (PAS) usually refers to one of the following areas:
OPC source redundancy
Multiple SCADA / DCS servers are provided in a standby arrangement. In this case, the Atmos Data Manager makes a connection to all of the OPC servers within the group and is able to switch between the various sources on fail-over to ensure maximum data availability. Atmos Data Manager employs several tests to verify the health of current connection such as the Watchdog check, Ping check, OPC server status check and can be configured to use custom server status signals read from the OPC Server.
Network and hardware redundancy
Duplication of hardware components such as power supply units, hard disks (RAID mirroring), and network interface cards (IP Teaming) is common in modern industrial systems. Ethernet networks are also designed with redundancy in the network infrastructure so that if there is a fault with any part of the link then it should be possible for the data to find an alternate path. Through the correct setup of Atmos Data Manager, the server NICs and the network components (switches, routers) it can be ensured that any downtime in the connection between SCADA and the PAS is minimized.
Pipeline application server redundancy
Multiple pipeline application servers are sometimes deployed in order to provide maximum system robustness. This can consist of multiple machines at the same location or replication between multiple sites. In either case, it is necessary for all of the servers in the redundant group to communicate with each other to co-ordinate Active/ Standby conditions and for the replication of data between the SQL databases on the machines. Server redundancy is managed by the Atmos SMT (system management tool) which monitors the health of the servers and co-ordinates the fail-over/ start-up/synchronization of the various modules on the machine such as leak detection, batch tracking, pig tracking, and hydraulic simulation.