Here are the steps to take backup of etcd cluster. My guess is etcd backup is same as taking snapshot of the db into local machine. Backing up Data_dir folder will take back up of the whole folder. It’s really what is the question given.

In terms of SQL database, taking backup of the database will be sqldump to a sql file and restoring it if needed.

Here are the steps to take database backup with correct version on the local machine from the given endpoint

1. curl -L https://github.com/coreos/etcd/releases/download/v3.3.1/etcd-v3.3.1-linux-amd64.tar.gz -o etcd-v3.3.1-linux-amd64.tar.gz

2. tar xzvf etcd-v3.3.1-linux-amd64.tar.gz

3. cd etcd-v3.3.1-linux-amd64

4. ETCDCTL_API=3 ./etcdctl --endpoints http://127.0.0.1:2379 snapshot save snapshotdb

5. ETCDCTL_API=3 ./etcdctl --write-out=table snapshot status snapshotdb # verify the snapshot

6. ETCDCTL_API=3 ./etcdctl snapshot restore snapshotdb # restore the backup

Please refer DR doc for etcd https://github.com/coreos/etcd/blob/master/Documentation/op-guide/recovery.md#restoring-a-cluster