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Except that (presumably) there is no guarantee that any spot instances are available. You could wind up in a state where you have no instances running. No user-

Except that (presumably) there is no guarantee that any spot instances are available. You could wind up in a state where you have no instances running. No user-facing production service can tolerate that.

roca 5y ago
Just spin up regular VMs if you can't get spot instances when you need them.
- deleted 5y ago
  [deleted]
- xyzzyz 5y ago
  Lack of spot VM means that all spare capacity has been taken up by the regular VMs, meaning that it spots are gone, so are regular ones.
  - roca 5y ago
    Maybe that's true but we haven't seen this happen in practice. Maybe we're just incredibly lucky but we're able to get on-demand instances to recover after spot termination.
  - apendleton 5y ago
    Having worked on infrastructure deployed this way, I can say this oversimplifies a bit. There's virtually never no spot capacity at all, there's no capacity at a given bid price, for a given instance type, in a given region. You can start to scale up on-demand infrastructure using spot price as a signal, before there's literally none left, and you can also run on clusters of heterogeneous instances, and change your instance type mix when one instance type's price goes up. In the worst case you can fail out of a particular region whose spot prices have gotten too high. Lots of options.
    - sitkack 5y ago
      No shade, but this is a very AWS specific view of cloud. Every cloud has a different resource allocation philosophy, not all the assumptions are the same.
      - remram 5y ago
        Yeah, GCP spot instances don't vary in price like AWS ("The price adjustments will occur at most once a month").
        ianburrell 5y ago
        There is no longer bidding for spot prices on AWS. They moved to model where pay the fixed spot price which isn't based on capacity. https://aws.amazon.com/blogs/compute/new-amazon-ec2-spot-pricing/ https://aws.amazon.com/blogs/compute/new-amazon-ec2-spot-pri...
        remram 5y ago
        Interesting! I think it still updates more than once a month, but that is a significant change that I wasn't aware of, thank you.
jayd16 5y ago
No guarantee but still very likely there are instances available.
jpdb 5y ago
Spot is excess capacity. If there's zero excess capacity, that means there's (probably) also no on-demand capacity as well.
- remram 5y ago
  If you are not being given any excess capacity, that doesn't mean there is no excess capacity. You are just not one of the lucky few, whose numbers are shrinking.
roland35 5y ago
I believe AWS can create spot autoscaling groups which include a minimum baseline traditional instances plus a floating level of spot instances. This seems to be a nice compromise.

roca 5y ago

Just spin up regular VMs if you can't get spot instances when you need them.

deleted 5y ago
[deleted]
xyzzyz 5y ago
Lack of spot VM means that all spare capacity has been taken up by the regular VMs, meaning that it spots are gone, so are regular ones.
- roca 5y ago
  Maybe that's true but we haven't seen this happen in practice. Maybe we're just incredibly lucky but we're able to get on-demand instances to recover after spot termination.
- apendleton 5y ago
  Having worked on infrastructure deployed this way, I can say this oversimplifies a bit. There's virtually never no spot capacity at all, there's no capacity at a given bid price, for a given instance type, in a given region. You can start to scale up on-demand infrastructure using spot price as a signal, before there's literally none left, and you can also run on clusters of heterogeneous instances, and change your instance type mix when one instance type's price goes up. In the worst case you can fail out of a particular region whose spot prices have gotten too high. Lots of options.
  - sitkack 5y ago
    No shade, but this is a very AWS specific view of cloud. Every cloud has a different resource allocation philosophy, not all the assumptions are the same.
    - remram 5y ago
      Yeah, GCP spot instances don't vary in price like AWS ("The price adjustments will occur at most once a month").
      - ianburrell 5y ago
        There is no longer bidding for spot prices on AWS. They moved to model where pay the fixed spot price which isn't based on capacity. https://aws.amazon.com/blogs/compute/new-amazon-ec2-spot-pricing/ https://aws.amazon.com/blogs/compute/new-amazon-ec2-spot-pri...
        remram 5y ago
        Interesting! I think it still updates more than once a month, but that is a significant change that I wasn't aware of, thank you.

jayd16 5y ago

No guarantee but still very likely there are instances available.

jpdb 5y ago

Spot is excess capacity. If there's zero excess capacity, that means there's (probably) also no on-demand capacity as well.

remram 5y ago
If you are not being given any excess capacity, that doesn't mean there is no excess capacity. You are just not one of the lucky few, whose numbers are shrinking.

roland35 5y ago

I believe AWS can create spot autoscaling groups which include a minimum baseline traditional instances plus a floating level of spot instances. This seems to be a nice compromise.