clarify doc
@@ -13,6 +13,10 @@ Please refer to [ent.](https://entgo.io/) [supported database](https://entgo.io/
- Gremlin
+!!! warning
+ When switching an existing instance of crowdsec to a new database backend, you need to register your machine(s) (ie. `cscli machines add -a`) and bouncer(s) to the new database, as data is not migrated.
+
+
## MySQL
Connect to your `MySQL` server and run the following commands:
