Alex Bublichenko

See repro steps in https://github.com/m3db/m3/issues/4125

By design, all shards must be available before any new instances can be added to aggregator placement because it requires reshuffling of shards across all instances: https://github.com/m3db/m3/blob/master/src/cluster/placement/algo/mirrored.go#L152 You might want...

Please provide more clear description of the problem.