"Shuffle sharding: Shard instances (combine them into small groups) to limit the number of instances a particular request source can reach, so that if that request source causes problems (a noisy neighbour), the number of instances impacted is limited (as opposed to full balancing of requests, where the requests could go to any instance, which could potentially impact all instances); Shuffle the shards so that any random shard can contain instances that overlap other shards giving many more shards, if a source request impacts a shard, other source requests going to other shards which include an impacted instance are only partially affected and since there are many more shards you are much less likely to be using the exact same shard as the bad one."