Some best practices on prevent the new started hosts(have not finished full sync) in Redis cluster to serve traffic from client

[ackerL]

One scenario in Redis cluster is that:

1. The new started host(slave) was added to the existing shard.
2. The slave will try to ask for full sync from the master
3. The master will fork a child process and execute BGSAVE.

There is issue that once step 1 finished, the new slave has started to serve traffics from clients, it will result in data miss as the new host has not completed the full sync(the data inconsistency between master and the new started slave).

I am wondering if there is way to prevent the not ready host serving traffics. The clients do not expect data miss caused by the not ready host.