At my current job, we're looking into DIs to reduce our SQL costs. With standard Spot/RIs, we're paying per-core for SQL Server. But with a DI, we're expecting to be able to license against the physical sockets instead.
> You can use Dedicated Hosts and Dedicated instances to launch Amazon EC2 instances on physical servers that are dedicated for your use. Dedicated Instances are Amazon EC2 instances that run in a VPC on hardware that's dedicated to a single customer. You can also use Dedicated Hosts to launch Amazon EC2 instances on physical servers that are dedicated for your use.
> Dedicated instances may share hardware with other instances from the same AWS account that are not Dedicated instances.
> An important difference between a Dedicated Host and a Dedicated instance is that a Dedicated Host gives you additional visibility and control over how instances are placed on a physical server, and you can consistently deploy your instances to the same physical server over time.
It looks like you can launch DIs on your DHs, or on any arbitrary host; but once you have a DI on an arbitrary host, only your VMs will run there; so a de facto Affinity policy. And any instance you launch on your DH is automatically a DI.
Is there a benefit to running DIs without having a DH? It sounds like having a DI gives you 90% of a DH. The DH gives you is a few hardware details (which might be essential for licensing), and like GP suggested would let you choose Affinity (or Anti-Affinity) between them manually.
As a result, Dedicated Hosts enable you to use your existing server-bound software licenses like Windows Server and address corporate compliance and regulatory requirements.
This is the first I'm hearing about DHs, and it sounds like that might be what we need, instead of the DIs we've been telling other teams about.
I'm not an expert on DI and DH, sorry. I can find answers for you though and post them back here. You can also email me: randhunt@amazon.com (actually anyone on these threads is welcome to email me any question they have) and I can try to get back to you there.
Dedicated Instances: https://aws.amazon.com/ec2/purchasing-options/dedicated-inst...
and
Dedicated Hosts: https://aws.amazon.com/ec2/dedicated-hosts/