I manage a large scale cloud based product that uses SQL Server as the database engine. The model is designed such that each customer using the product has its own instance of MS SQL Server. I'm needing a way to query, update, and insert in these instances from a centralized SQL instance that is used to handle administration of the instances. I've already determined that creating linked server objects is the way to go, and it's how I've been handling ad hoc updates from these databases already. I'm working on expanding some functionality which will result in a significant increase in the amount and frequency of queries being executed from this centralized administration instance.
So, here is my question: What is the impact of having 100+ linked server objects open all the time from a single SQL instance? Is there any impact at all? Up to this point, my practice with linked servers has been to drop them once I'm done.