(Optional, a number) Spreads load over the hosts that are about equally good. Normally the best-scoring host wins; when several requests arrive within a short time, they would all land on the same host, as its load only shows after the VM starts. With this set, any host scoring at least (1 - deviation) times the best score is as good as the best one, and one of them is picked at random. The build log says when that happened.

• 0 (the default): choose randomly only among hosts with exactly the best score.
• e.g. 0.1: hosts within 10% of the best score are all candidates.
• 1: all hosts that pass the filters are candidates.
• above 1 (e.g. 2): choose any available host at random, whatever its load: reachable, not in maintenance, among the candidate hosts and not too small (where its size is known), including hosts that report no usage statistics. The free resource limits and the free RAM requirement, which need usage figures, are not applied.
• a negative number: always take the single top host (the first one on a tie).