Since a couple of weeks our SQL Server is behaving strangely:
- Query deadlocks started occurring
- Some queries timeout
- Access to folders sometimes is laggy
No changes have been done to databases, and no, there has not been an increase in rows in the involved databases. Indexes have been rebuilt, and are constantly maintained.
The lightpath (Automatic diagnostics for the server) on the server doesn't show any error.
What's the checklist to start pinpointing the culprit? Ideally without having to run offline diagnostics, but if there's no other choice, so be it.