Hi Maxime Rouillard,
In clustering, we let the following directories (recursively) be synchronized across the nodes:
```
/opt/gluu/jetty/oxauth/custom/
/opt/gluu/jetty/identity/custom/
/opt/gluu/jetty/identity/conf/shibboleth3/idp/
/opt/gluu/jetty/identity/conf/shibboleth3/sp/
/opt/shibboleth-idp/conf
/opt/shibboleth-idp/metadata/
/opt/shibboleth-idp/sp/
/opt/shibboleth-idp/temp_metadata/
/etc/gluu/conf/
```
Let me know if this helps.
Regards.