Comparison
Bin packingvsRightsizing
Bin packing
the cluster is at ninety percent booked and forty percent used, and adding one more workload still needs a whole new node.
Fitting workloads of assorted sizes onto as few nodes as possible. It is the lever that converts requests into a bill: efficiency is set by how honest requests are and by the ratio of the largest workload to the node size, since one big request can leave an unusable remainder on every node. It is also the reason a cluster can be simultaneously expensive and underused, which reads as a paradox until you look at requests rather than usage.
Full entry →Rightsizing
you look at a fortnight of real usage and cut the requests in half, and nothing at all happens.
Matching provisioned resources to observed usage plus deliberate headroom. It is unglamorous, repeatable and usually the single largest available saving, and it decays continuously as workloads change, so it is a recurring exercise rather than a project. The risk is rightsizing to an average and discovering the peak, which is why the percentile you size to should be a decision rather than an accident.
Full entry →