在Rails应用程序中存储全局变量的最佳位置是哪里?

I was wondering if there is the best practice on where to store global settings in a rails app. What I mean by that is i.e: I have a few globals defined that may change, but not likely and it seems inappropriate to store them in DB since they are used so much. For instance I have SYSTEM_EMAIL & SYSTEM_EMAIL_SIGNATURE & SYSTEM_STORAGE_ROOT. I was wondering if there is the best practice o