I have had a look at the database/persistence related forums in the Saloon, and I have only found two: the one about O-R mappings, and the one about JDBC. However, there is not good place to ask questions about object databases, for instance.
I think having a general "Persistence" forum would not hurt.
In programming, persistence refers specifically to the ability to retain data structures between program executions, such as, for example, an image editing program saving complex selections or a word processor saving undo history.
This is achieved in practice by storing the data in non-volatile storage such as a file system or a relational database or an object database.
I think it may be a big enough topic (may also include serialization). But since I am new around here, and you are the sherrifs, I guess you know better what needs a forum and what not.
Else you'd have a forum where 90% of the posts would just end up being moved somewhere else and the rest be posts like "what persistence technology is best" (without of course mentioning a specific scenario because that would almost always make the post more relevant in a more specific forum).