> If every request took exactly the same amount of cpu time and wall time and same amount of ram and other resources, then random load-balancing is just fine fo

> If every request took exactly the same amount of cpu time and wall time and same amount of ram and other resources, then random load-balancing is just fine for a sufficiently large number of machines. The article points out random load balancing scales sub-linearly with increase in capacity? If we distribute a set of items randomly across a set of servers (e.g. by hashing, or by randomly selecting a server), the average number of items on each server is num_items / num_servers. It is easy to assume this means each server has close to the same number of items. However, since we are selecting servers at random, they will have different numbers of items, and the imbalance can be important. ... This is a classic balls in bins problem... the summary is that the imbalance depends on the expected number of items per server (that is, num_items / num_servers). This means workload is more balanced with fewer servers, or with more items. This means that dividing a set of items over more servers makes the distribution more unfair, which is a reason we can get worse than linear scaling of a distributed system.*