Disconnected Startup Requirements

Interface

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  The interface must be built against UniInt version 4.3.0.x or later.
  
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  The interface node must have PI API version 1.6.1.5 or later installed.
  
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  The interface must not utilize the PI SDK to retrieve the extended point attributes from the PI Server.
  
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  The host PI Server must be version 3.x or later.
  

Buffering

The interface node must have the PI Buffering service installed and configured to buffer data to prevent data loss while starting the interface in the disconnected startup configuration when the host PI Server is not available. Prior to the disconnected startup feature, the interface could not start without a connection to the PI Server because the point configuration data needed to start the interface could only be retrieved from the PI Server. However, with disconnected startup, the interface receives point configuration data from the cache files when no PI Server connection is available. If the buffering service is not running while the PI Server is unavailable, the benefit of being able to start the interface without a connection to the PI Server is negated. Moreover, any data collected while the connection to the PI Server is unavailable would be permanently lost.
There are two buffing services available; API Buffer Server and the PI Buffer Subsystem. API Node buffering (BufServ) refers to functionality in the PI API that supports continuous collection of data on an API Node regardless of the status of the destination PI server or the network link to the PI server. The Buffer Subsystem (PIBufss) is a new component of the PI System, primarily designed to enhance the High Availability (HA) features of the PI Server. PIBufss is different from the API Buffer Server, even though it has most of the same capabilities and more.
The Buffer Subsystem offers significant benefits over the API Buffer Server, but does not replace it entirely. PIBufss has advantages over Bufserv when connected to redundant PI servers, configured as a Collective (PI Server Replication) for High Availability (HA). These PI Servers must be running OSIsoft Platform Release 1 (PR1) or a later version.
The PI API/BufServ 1.6.1.x introduced buffering to multiple PI Servers from a single machine. This includes buffering to replicated PI Servers that are part of a single PI Collective. However, BufServ does not detect and validate the PI Collective configuration and as a result, requires manual configuration. Additionally, due to the independent data compression taking place in the Snapshot Subsystem (at each replicated PI Server), BufServ does not guarantee identical records in the PI Archive.
Detailed documentation for configuring and running API Node Buffering can be found in the PI SDK Help (pisdk.chm, which embeds the piapi.chm file). The help file is located in the PIHOME\PIPC\Help\ directory. The configuration details for the Buffer Subsystem can be found in the PI Buffer Subsystem Help (pibufss.chm file).

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