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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 insta

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)

johngladtj 3y ago
Electricity costs money
- JW_00000 3y ago
  But no electricity is used if your instance is up but idle.
  - tsimionescu 3y ago
    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.
- littlestymaar 3y ago
  The electricity overhead of keeping an idle VM on an already running host is nearly zero though.
  - tsimionescu 3y ago
    Sure, but the electricity overhead of keeping one host running just to run an idle VM is not as trivial.
    - littlestymaar 3y ago
      But that's not what's happening: they aren't keeping a full host for you. Your argument is like saying that a bus traveler costs the gas needed to power the bus, but it's never the case: the bus would be cruising no matter what. And symmetrically the VM host would be up no matter what you did with your instance.
      - tsimionescu 3y ago
        I'm not sure that's true. Shutting down unneeded hardware seems like a very simple but major optimization.
        littlestymaar 3y ago
        You assume that the hardware would be unneeded, but that's a very strong assumption. It would be very bad for any cloud provider to leave hosts with only one VM running on it, and you can be pretty sure only very small minority of their park that end up in that situation where shutting down a single VM would lead to a shut-down of the entire host, because it means that the host was vastly under-used in the first place.
        tsimionescu 3y ago
        As far as I know, most cloud hosts don't actually support automatically moving live VMs, so I think it's fairly common for a host to be left running a single VM. At least in AWS, they never supported this, and in fact may require you to reboot an instance occasionally in order for it to be moved to a new hardware host (typically when they are upgrading their hardware).
        littlestymaar 3y ago
        But why are you talking about moving VMs?! Looks like you're adding tons of far-fetched speculations at every step of your reasoning. The way you easily deal with this issue is very simple and does not require moving VMs: you just allocate newly spawned VMs to existing hosts with available room! When you do so (and they obviously all do!) you end up with little unused hardware…
pxeger1 3y ago
“There is a good chance it costs them $0” = “in expectation it costs them >$0”
littlestymaar 3y ago
This exactly.

johngladtj 3y ago

Electricity costs money

JW_00000 3y ago
But no electricity is used if your instance is up but idle.
- tsimionescu 3y ago
  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.
littlestymaar 3y ago
The electricity overhead of keeping an idle VM on an already running host is nearly zero though.
- tsimionescu 3y ago
  Sure, but the electricity overhead of keeping one host running just to run an idle VM is not as trivial.
  - littlestymaar 3y ago
    But that's not what's happening: they aren't keeping a full host for you. Your argument is like saying that a bus traveler costs the gas needed to power the bus, but it's never the case: the bus would be cruising no matter what. And symmetrically the VM host would be up no matter what you did with your instance.
    - tsimionescu 3y ago
      I'm not sure that's true. Shutting down unneeded hardware seems like a very simple but major optimization.
      - littlestymaar 3y ago
        You assume that the hardware would be unneeded, but that's a very strong assumption. It would be very bad for any cloud provider to leave hosts with only one VM running on it, and you can be pretty sure only very small minority of their park that end up in that situation where shutting down a single VM would lead to a shut-down of the entire host, because it means that the host was vastly under-used in the first place.
        tsimionescu 3y ago
        As far as I know, most cloud hosts don't actually support automatically moving live VMs, so I think it's fairly common for a host to be left running a single VM. At least in AWS, they never supported this, and in fact may require you to reboot an instance occasionally in order for it to be moved to a new hardware host (typically when they are upgrading their hardware).
        littlestymaar 3y ago
        But why are you talking about moving VMs?! Looks like you're adding tons of far-fetched speculations at every step of your reasoning. The way you easily deal with this issue is very simple and does not require moving VMs: you just allocate newly spawned VMs to existing hosts with available room! When you do so (and they obviously all do!) you end up with little unused hardware…

pxeger1 3y ago

“There is a good chance it costs them $0” = “in expectation it costs them >$0”

littlestymaar 3y ago

This exactly.