I'm very glad to see you trying out InnoDB Cluster and MySQL Enterprise Backup!
The best place to ask questions about MySQL Enterprise is support.mysql.com. There you can be sure to find fast resolution to any MySQL related question or problem you may have. There you can browse the customer knowledge base, as well as open an unlimited number of support requests--answered by the world's leading MySQL experts and backed by the MySQL development teams. I would strongly encourage you to leverage the virtually unlimited MySQL expertise you have available to you there. :)
That being said, we cover this very topic in detail within the following KB articles:
- Backup and Restore Of Group Replication Node (Single + Multi Primary): https://support.oracle.com/epmos/faces/DocumentDisplay?id=2276610.1
- Getting Started With MySQL Group Replication: https://support.oracle.com/epmos/faces/DocumentDisplay?id=2212994.1
In short, you have two options when using the MySQL Enterprise Backup client (mysqlbackup) with Group Replication / InnoDB clusters:
1. Take a standard backup from the current primary
2. Take a backup from a current secondary using the --no-history-logging option so that mysqlbackup doesn't try and execute DDL and DML for the history tables (https://dev.mysql.com/doc/mysql-enterprise-backup/4.1/en/backup-metadata-options.html#option_meb_no-history-logging)
For more general info, you can also see the "Master Note for MySQL Group Replication and InnoDB Cluster": https://support.oracle.com/epmos/faces/DocumentDisplay?id=2215424.1
Thank you for using InnoDB Cluster and Enterprise Backup!