What is the use of prompts in Framework Manager?

Use of Prompt in Framework Manager:

Filter on query subject - to restrict the rows that are returned by filtering out the unwanted data by creating one or more embedded filters for query subject.

prompt in filter with usage set to always - user need to supply a value to filter.
propmt in filter with usage set to optional - user need to supply a value for the filter / if user dont supply a value, filter will not be applied.

Generally cube size is 2GB only but if we want to increase the cube size then we need to go to partition scenario.

For exp: I am creating one cube with year basis that means that year cube having 2 GB but my data was exceeded then 2GB of cube size then I have to apply partition the cube based on Timebase partition on Month then what happened there are 12 months cubes created and summary data maintained by Year cube that means 12 * 2 GB=24GB capacity increased. Again it exceeded then go for fortnight (15 days) partition then again 48 GB capacity increased to main cube.