I read https://premium.wpmudev.org/project/multi-db/installation/ and i install step by step.
Now I'm using 4096 db on Vps.And i launched a blog for testing.
4096 db are empty,and my posts are going global db.Did I made a mistake in the installation?
I think that, after the 5000 blog the other databases might be used.
Thanks for helping (and sorry for my bad english)