The author of AutoSpotting here, glad to see it mentioned in here and happy to help clarify such issues.
Are you sharing this as an experience of using AutoSpotting or other mechanisms to launch Spot instances?
What you described may still happen occasionally and it happened a lot with older versions, but the recent versions of AutoSpotting, especially the commercial edition available on the AWS Marketplace (although the community edition available on GitHub also does it to some degree) should avoid such situations in the default configuration should be much more reliable than before.
Actually when it comes to capacity, when Spot capacity is not available and we failover to on-demand, the latest AutoSpotting version will failover between multiple instance types with the same diversification used for Spot instances so you're pretty much guaranteed to have capacity even better than your initial single-instance ASG.
We also use the capacity-optimized-prioritized allocation strategy with a custom priority based on lowest cost, but also preferring recent instance types if available for more performance and lower carbon emissions.
Let me know if you have further questions about AutoSpotting, Im happy to help.
Are you sharing this as an experience of using AutoSpotting or other mechanisms to launch Spot instances?
What you described may still happen occasionally and it happened a lot with older versions, but the recent versions of AutoSpotting, especially the commercial edition available on the AWS Marketplace (although the community edition available on GitHub also does it to some degree) should avoid such situations in the default configuration should be much more reliable than before.
Actually when it comes to capacity, when Spot capacity is not available and we failover to on-demand, the latest AutoSpotting version will failover between multiple instance types with the same diversification used for Spot instances so you're pretty much guaranteed to have capacity even better than your initial single-instance ASG.
We also use the capacity-optimized-prioritized allocation strategy with a custom priority based on lowest cost, but also preferring recent instance types if available for more performance and lower carbon emissions.
Let me know if you have further questions about AutoSpotting, Im happy to help.