Elastigroup Flexible Instance Size For Reserved Instances

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We are happy to announce our latest support in Flexible Instance size for Reserved Instances which will allow our customers to reduce their compute costs even more with a simple one-click configuration!


Utilizing Reserved Instances at Scale with Elastigroup

What Are Reserved Instances?

Reserved Instances provide you with a significant discount compared to on-demand Instance pricing. Reserved Instances are not physical instances, but rather a billing discount applied to the use of on-demand Instances in your account.

What has changed?

Up to this point, when purchasing a reservation, your on-demand servers had to be of the exact specific instance type (same instance family and size) to utilize the reservation, Now with flexible reservation, the restriction is per instance family, that means that multiple smaller instances can be a utilize one larger reservation.

How it works?

Spotinst enumerates all the on-demand and reserved instances in your account repeatedly, analyze their utilization, and upon scale up / EC2 Instance provisioning decides what will be cheaper – requesting a new EC2 Spot Instance or Launching an on-demand instance that fits the reservation.




Your account has a reservation for m4.4xlarge which is 50% utilized, and your Elastigroup needs to scale up by 2 instances of m4.xlarge,m3.xlarge or c4.xlarge, Spotinst will automatically start 2 on-demand m4.xlarge servers to utilize the entire reservation. If you will start another m4.xlarge on-demand server that meets the criteria for the reservation, Spotinst will automatically free a space for it on your reservation by changing one of its Elastigroup on-demand instances to optimize costs.

How do I configure it?

All you need to do is to check the “Utilize Reserved Instances” option located in the Elastigroup’s ‘General Configuration’ tab under the ‘Advanced’ section, sit back, let Spotinst take care of the rest.


Aviv Shukron,

Product Management, Spotinst.