if you need to restart PI Base Subsystem, this is like taking the PI Data Archive offline. Clients and Interfaces should be able to re-connect as soon as PI Base Subsystem service is running again but you should take a close look at the PI Message Log to make sure everything goes back to "normal" operation.
We strongly recommend to install data collection software like PI Interfaces remote to the PI Data Archive and to enable PI Buffer Subsystem. This way, data collection should not be affected. If you followed our recommendations, you should be fine.
