<!-- STOP -- PLEASE READ! GitHub issue is not the right place for support requests. If you're looking for help, check the Discussions (https://github.com/juicedata/juicefs/discussions). You can also post your question on the Discussions or the JuiceFS Slack channel (https://juicefs.slack.com). --> 取redis-cluster作为元数据存储，建议支持指定 key前缀，方便统一管理
