# Considerations when using an external metastore
<a name="external-metastore-considerations"></a>
+ You can configure databases that are compatible with MariaDB JDBC as your metastore. Examples of these databases are RDS for MariaDB, MySQL, and Amazon Aurora.
+ Metastores aren't auto-initialized. If your metastore isn't initialized with a schema for your Hive version, use the [Hive Schema Tool](https://cwiki.apache.org/confluence/display/Hive/Hive+Schema+Tool).
+ EMR Serverless doesn't support Kerberos authentication. You can't use a thrift metastore server with Kerberos authentication with EMR Serverless Spark or Hive jobs.
+ You must configure VPC access to use the multi-catalog hierarchy.