difference between 'etcdctl2 backup' and 'etcdctl3 snapshot save'

[anpingli]

In etcd3.x, there are two backup commands 'etcdctl backup(v2 API )' and 'etcdctl snapshot save(v3 API)'. I had make some testing about backup/ restore . I have some questions.

etcdctl2 can backup v2 API data and It didn't copy snap/db files. But the file snap/db are required during restore. Shall I backup snap/db by manually copy it ? Is there any risk to restore with this manually backed snap/db?

There is an option '--keep-cluster-id' for etcdctl2 backup. but I couldn't restore with cluster-id. Does this option work?

etcdctl2 backup also support v3 API. Could we use it to backup v3 data? Is there any risk?

What is the benefit of etcdctl2 snapshot save/restore? Must we to use etcdctl3 snapshot save/restore with v3 API data?

[heyitsanthony]

etcdctl2 can backup v2 API data and It didn't copy snap/db files. But the file snap/db are required during restore. Shall I backup snap/db by manually copy it ? Is there any risk to restore with this manually backed snap/db?

I don't think this is safe if done while etcd is still accepting proposals. etcd may complain about the db index not matching raft indexes from the backup. There's currently no way to safely backup both v2 and v3 data together (see #7002).

There is an option '--keep-cluster-id' for etcdctl2 backup. but I couldn't restore with cluster-id. Does this option work?

Restore usually needs --force-new-cluster. See the v2 admin guide

What is the benefit of etcdctl2 snapshot save/restore?

There is no v2 etcdctl snapshot command; it's v3 only.

Must we to use etcdctl3 snapshot save/restore with v3 API data?

Yes.

[anpingli]

@heyitsanthony Thanks for you reply.