Start with a running cluster (a 1-node cluster is enough) with lots of data, e.g.:
$ etcd --name 0 --listen-peer-urls=http://localhost:2380 --listen-client-urls=http://localhost:2379 -advertise-client-urls=http://localhost:2379 --initial-cluster-state=new --snapshot-count=100 --debug=true --log-package-levels "*=DEBUG"