GE Embedded Field Agent, Руководство пользователя

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GFK-2993F 84
For public disclosure
6.2.5.4 Using Store and Forward When Internet Connectivity is Disrupted and Restored
At a publish rate of 100 4-Byte Variables every second, the Mini Field Agent can store data for one hour when Internet
connectivity has been disrupted. At maximum load, the Embedded Field Agent can store data for 24 hours when Internet
connectivity has been disrupted. When the StoreForward database becomes full, the Field Agent will stop storing new data until
Internet connectivity is restored and 60% of the stored data has been forwarded to the Predix Time Series Database. Stored data
values are forwarded in chronological order.
Note
Because the processes that store and forward data values run asynchronously, new data values must be stored to the
StoreForward database before being forwarded to the Predix Time Series Database. When Internet connectivity is restored after
the StoreForward database has reached maximum capacity, 60% of the stored data must be forwarded to the Predix Time Series
Database before new data values will be stored in the StoreForward database. The time required to forward this stored data
depends on the available upload bandwidth.
Note
On the MFA, the StoreForward database is not retained when power is lost or when restarted.
The StoreForward database is a buffer that has a maximum size, a fill rate, and an empty rate.
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The maximum size of the StoreForward database is fixed on the Field Agent and cannot be adjusted.
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The fill rate of the StoreForward database can be adjusted by either changing the number of variables published,
changing the publication interval of the configured variables, or both. The fill rate is determined by the fastest
publication interval in use and the number of variables published.
o
The maximum time that it takes to fill the StoreForward database increases inversely based on the fill rate
of the database. The following illustrates the relationship between variables published and fill rate:
Effect of Variables Published Per Interval on StoreForward Fill Time
o
The maximum time that it takes to fill the StoreForward database is limited to twelve hours on the MFA
and 72 hours (three days) on the EFA.
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The maximum empty rate of the StoreForward database is fixed on the Field Agent and cannot be adjusted. The
empty rate is influenced by network bandwidth and latency to the Time Series Database endpoint.