The startup process of any system is a very interesting stage. Ever since I was exposed to the world of computers, I was fascinated with the POST (Power On Self Test) sequence, about which I learnt and explored in detail when I studied Electronics & Communications engineering. SQL Server is a server system on it’s own and therefore, I recently had a yearning for learning about the SQL Server startup sequence.
Now, I know that the SQL Server startup process involves an Undo-Redo phase for rolling forward/backward open transactions in each database, but the questions that kept cropping up in my mind were:
- When the SQL Server starts, what is the first database that is made online? Answer: Master
- When are user databases made available in the startup sequence? Answer: After all system databases have been recovered
- When is the tempdb available? Answer: After the master, resource and model databases are recovered (in that sequence)