Streams are the main data gathering mechanism of Entuity's StormWorks architecture, and they define properties of the polling process.
The polled data retention of a stream will depend on the data being collected. The data retention for a given server can be seen in that server's Data Dictionary. The Data Dictionary is rewritten by the Configure process to reflect any custom changes made to the system.
There are instances where you can specify data retention through the UI. These are: