Comment by Johnny555
1 year ago
That’s not because hosting instances doesn’t actually cost Amazon anything
Except it doesn't cost them anything. The marginal cost of keeping your single instance running is $0 (unless they were 100% out of capacity and they could have sold that instance to someone else either at full price or spot price)
Electricity costs money
The electricity overhead of keeping an idle VM on an already running host is nearly zero though.
Sure, but the electricity overhead of keeping one host running just to run an idle VM is not as trivial.
9 replies →
But no electricity is used if your instance is up but idle.
What does "idle" mean? Both a Linux or Windows OS not running any active software will still do computation and even network traffic (disk cache wrangling, indexing, checking for updates, NTP clock syncing etc), and requires electricity to do so.
It's very low cost, especially if its on a VM from a host that otherwise runs other VMs, but it's not 0. And if it happens to be the last VM preventing a hardware server from completely powering off, then it's actually quite far from 0.
“There is a good chance it costs them $0” = “in expectation it costs them >$0”
This exactly.