author here: this is why i suggest to use mix of reserved instances and spot instances. worse case scenario, everything will be on the small number of reserved

author here: this is why i suggest to use mix of reserved instances and spot instances. worse case scenario, everything will be on the small number of reserved + on-demand instances. there are other strategies to avoid this as well using multiple type of instance, of different sizes, on different availability zones. because price spike is different for each combinations using bigger size instance than usual because bigger = more stable / less likely to get evicted