Comparison
Bin packingvsUnschedulable workload
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 →Unschedulable workload
the deploy has been sitting at pending for twenty minutes with no error, because no node satisfies every constraint you set.
A workload the scheduler cannot place, left waiting rather than failed. The scheduler's own event explains why in one line — insufficient memory, no matching label, untolerated taint, unsatisfiable anti-affinity — and reading it is invariably faster than reasoning about it. It is the most common form of 'the deploy is stuck', and it looks like nothing is happening because, precisely, nothing is.
Full entry →