- Now let's talk about single versus multi-tenant instances.
Within AWS within EC2, we have the ability to achieve
either a single tenant or multi-tenant environment
at least when it comes within the context
of our actual instance.
Keep in mind that the rack in the data center those
will always be multi tenant there will always be more
than one customer using the actual rack
in the data center.
But the actual compute we do have the ability to limit
that to a single tenant environment.
So in this particular diagram,
we have a physical host
that's running EC2 instances right?
So within AWS we have
here the physical host right?
The Rack, the Chassis, the Motherboard, the Processor
being Intel Xeon memory and network cards
and all those things that make up that physical server.
And then of course we have the Hypervisor.
Now all of these things are Amazon's responsibility.
In terms of the shared responsibility model,
AWS is responsible for building and supplying
and maintaining and securing this physical host.
When it comes to launching EC2 instances,
AWS is responsible for installing the operating system
on these instances but once it's running,
we as customers are responsible for maintaining
that operating system.
And so the default environment for these EC2 instances
if we don't choose something else.
The default environment would be that
each one of these may very well
be a different customer right?
So we may have customer one over here,
we may have customer two and over here
we may have customer three right?
So the default behavior might be that
we have different customers all running
and essentially sharing the same underlying physical host
and from many cases that's perfectly fine.
In fact PCI in HIPAA recently
within the last, I'm not sure exactly when
but within the last year or two, PCI and HIPAA both updated
their policies to allow multi-tenant environments
in many cases right?
So if you do need a single tenant environment,
we have two options.
If you need to be the only customer
that is essentially running across this physical host,
if you need to be the only customer with these
managing any instances on this host.
Then we could leverage what we call Dedicated Instances.
And Dedicated Instances simply means that
even though we're running a virtual instance
on that physical host, we are the only customer.
In some other cases we may need to actually
have some type of affinity with the physical host
and so especially for enterprises who need
to migrate applications whose licenses
are somehow tied to the physical host,
we gain access to that as well.
And so with a Dedicated Host right?
I'm just gonna write DH here for Dedicated Host.
With a Dedicated Host AWS essentially assigns one
of these physical hosts to us
and they give us the IDs they give us the core counts
and any information we would need about that host
in order to satisfy the licensing requirements
for our software that were migrating.
And then later when we go to launch EC2 instances
we can choose an affinity.
If we had multiple dedicated hosts, we could choose
which host we wanted that virtual machine
to be launched on right?
So let's keep that in mind for those of us
who may have a need to run in a single tenant environment
within EC2 the default behavior is multi tenant.
We have the option to go to single tenant
with either Dedicated Instances or Dedicated Hosts.