We're sensitive enough that we preemptively scale as traffic "appears" to be increasing. So we add 5 EC2 instances, not at crisis levels of traffic, but "Hmmm...I feel a tingling in my extremities". We then remove one instance at a time if traffic falls below "Not doing anything" levels. The time between scaling actions is 15 minutes. Since ASG's go to remove older instances first, we don't end up getting charged a full hour for instances that are up for less than an hour that often.
Admittedly, our web traffic is very US Business Hours centric and peaks predictably between 3 and 4 in the afternoon.
Also, we're operating more at a scale of $40,000/month for peak traffic capacity 24/7 and $25,000/month once I got autoscaling worked out. So...yeah. I guess the scale for savings matters. :-)
Admittedly, our web traffic is very US Business Hours centric and peaks predictably between 3 and 4 in the afternoon.
Also, we're operating more at a scale of $40,000/month for peak traffic capacity 24/7 and $25,000/month once I got autoscaling worked out. So...yeah. I guess the scale for savings matters. :-)