AVEVA PI System components with high availability

Now, consider all of the PI System components, and the high availability features that are supported.

Highly available PI System configurations range from small systems with a primary Data Archive server, PI AF server, and SQL Server on the same computer to larger systems that include a secondary Data Archive server and AF server on a different computer. The primary interface node and one or more secondary interface nodes support failover and buffering.

For distributed systems with large workloads and PI point counts, and with multiple Data Archive servers or Data Archive collectives that link to a central PI AF database, we recommend that you install Data Archive collectives and Microsoft SQL Server on separate, redundant computers to achieve the best level of performance and scalability.

High availability capabilities are available for all components in the PI System:

High availability features are available for all PI System components:

• Data sources

  Data sources can be configured to support redundant, replicated nodes.

• Interfaces

  A primary interface node and one or more secondary interface nodes ensures failover so that time-series data reaches Data Archive even if one interface fails. Buffering ensures that identical time-series data reaches each Data Archive server in a collective. When one interface is unavailable, the redundant interface automatically starts collecting, buffering, and sending data to Data Archive.

• Data Archive server

  To implement high availability, install more than one Data Archive server and configure the PI System to store and write identical data on each server. Together, this set of servers, called a Data Archive collective, acts as the logical Data Archive server for your system. These computers can be geographically dispersed. The collective receives data from one or more interfaces and responds to requests for data from one or more clients. Because more than one server contains your system data, system reliability increases. If one server becomes unavailable, another server contains the same data and responds to requests for that data. Similarly, when demand for accessing data is high, you can spread that demand among the servers.

• Asset Framework

  To implement HA you can configure multiple instances of PI AF application service in a Windows Failover Cluster or Network Load Balancer deployment. In addition, you can configure Microsoft SQL Servers in an AlwaysOn Availability Group, Mirrored SQL Server System, or as a Failover Cluster. For further information see the AVEVA PI Server™ Installation and Configuration chapter on PI AF server installation.

• Asset Analytics and Notifications

  To implement high availability for Asset Analytics and Notifications, install the PI Analysis service and the PI Notifications service in each node of a failover cluster. For more information, see the AVEVA PI Server™ Installation and Configuration topics on how to install these services in a failover cluster.

• PI Data Access

  The PI Data Access products PI OLEDB Enterprise, PI OLEDB Provider and PI Web Services support high availability. PI OLEDB Enterprise supports connection failover to servers in a PI collective when used with PI Asset Framework 2010 and later.

  PI Web Services retrieves data from either the primary or second member PI collective, using connection information from its host machine. PI OLEDB Enterprise and PI OLEDB Provider clients connect to collectives according to connection preference settings; you can also use PI System utilities to select another server in the collective.

  If a server in the collective becomes unavailable, SQL statements that are in progress might fail. This occurs if a PI OLEDB Enterprise or PI OLEDB Provider client cannot connect to an unavailable server, or reconnect to another collective member, within the time set for the Command Timeout. To avoid this timeout, increase the Command Timeout property in the OLE DB client, which is by default set to 60 seconds. For more information, see the user guides for PI OLEDB Enterprise or PI OLEDB Provider, which are available on the customer portal.

• Client applications

  To implement high availability at the PI client layer, configure clients to connect to any server in a Data Archive collective and switch to another server if necessary, without requiring any user intervention to fail over from one server to another. Clients can be configured to support redundant, replicated nodes.

  You can automatically direct client requests to the server with the most workload capacity. Client applications can start on any server. Applications are not required to be aware of any particular server. You can distribute connections and workloads among servers, reducing demands on individual servers.