CLUSTER SLAVES node-id
The command provides a list of slave nodes replicating from the specified
master node. The list is provided in the same format used by CLUSTER NODES (please refer to its documentation for the specification of the format).
The command will fail if the specified node is not known or if it is not
a master according to the node table of the node receiving the command.
Note that if a slave is added, moved, or removed from a given master node,
and we ask CLUSTER SLAVES to a node that has not yet received the
configuration update, it may show stale information. However eventually
(in a matter of seconds if there are no network partitions) all the nodes
will agree about the set of nodes associated with a given master.
The command returns data in the same format as CLUSTER NODES.