Rockwell Automation FactoryTalk Historian SE 3.0 H2H Interface User Guide - Manual (Page 111)

FactoryTalk Historian To Historian Interface User Guide 105
Chapter 13.
Buffering
Buffering refers to an interface node‟s ability to temporarily store the data that interfaces
collect and to forward these data to the appropriate Historian Servers. Rockwell Automation
strongly recommends that you enable buffering on your interface nodes. Otherwise, if the
interface node stops communicating with the Historian Server, you lose the data that your
interfaces collect.
The PI SDK installation kit installs two buffering applications: the PI Buffer Subsystem
(PIBufss) and the PI API Buffer Server (Bufserv). PIBufss and Bufserv are mutually
exclusive; that is, on a particular computer, you can run only one of them at any given time.
If you have Historian Servers that are part of a Historian Collective, PIBufss supports n-way
buffering. N-way buffering refers to the ability of a buffering application to send the same
data to each of the Historian Servers in a Historian Collective. (Bufserv also supports n-way
buffering, but Rockwell Automation recommends that you run PIBufss instead.)
Which Buffering Application to Use
You should use PIBufss whenever possible because it offers better throughput than Bufserv.
In addition, if the interfaces on an interface node are sending data to a Historian Collective,
PIBufss guarantees identical data in the archive records of all the Historian Servers that are
part of that collective.
You can use PIBufss only under the following conditions:

the Historian Server version is at least 2.x.x; and

all of the interfaces running on the interface node send data to the same Historian
Server or to the same Historian Collective.
If any of the following scenarios apply, you must use Bufserv:

the Historian Server version is earlier than 2.x.x; or

the interface node runs multiple interfaces, and these interfaces send data to multiple
Historian Servers that are not part of a single Historian Collective.
If an interface node runs multiple interfaces, and these interfaces send data to two or more
Historian Collectives, then neither PIBufss nor Bufserv is appropriate. The reason is that
PIBufss and Bufserv can buffer data only to a single collective. If you need to buffer to more
than one Historian Collective, you need to use two or more interface nodes to run your
interfaces.
It is technically possible to run Bufserv on the Historian Server Node. However, Rockwell
Automation does not recommend this configuration.