If one node crashes on DC setup, user-session information stored on that node will be gone, and the user will need to authenticate again.

The solution for this is to use SSO or remember me cookie functionality, but they will also show invalid session:

The user will not need to enter credentials but he will need to reload the page.

It would be a good solution to introduce Redis or some other caching mechanism so that the user login information is not lost if one node crashes. Alternatively, as with the Crowd, we could store session information inside the DB, and the application can retrieve it if there is no information in the cache.