The SAT equipment shall be installed and available (ready for use) in the establishment. If you refer to the Commercial Application database used in the establishment, Brazilian tax law requires that data be available on servers within the national territory, but this varies from state to state.
Just to illustrate, in States that have joined the PAF-ECF (which has nothing to do with the SAT) the database is required to be available in the establishment (unless this has changed since 2014).
In the State of São Paulo the taxpayer who issues SAT-CF tax documents and should be concerned to securely archive the signed XML files, which have legal validity and are the tax document itself (exist only in electronic form).
Details are in the CAT-147/2012 legislation available on the website Secretary of Finance of the State of São Paulo.
Thank you for clarifying my doubt.
– Marco