We're working on setting up Oracle's Enterprise Single-Sign-On with High Availability. At the moment every component provides HA except our database backend (i.e. we have just one instance).

While conducting some kick-the-plug tests we learnt that the ESSO system works even with the database turned OFF.

This was a nice surprise but now we need to understand what are the implications of a database failure; sure the sessions might be handled on the application servers and the policies might have been cached but... for how long? how big is this cache? what is the role of the database?

I would appreciate if anyone shares her/his experience and/or points out to documentation that covers this.

Thank you so much.