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Purpose
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This section describes the basic RHEL subscription model which generally
applies to most Red Hat products.  This section has language which has been
reviewed and approved by the legal department.  Do not alter this section
without prior approval from legal.

For further details or to resolve specific queries about subscriptions which
arise during a consulting engagement, customers should be directed to their
Red Hat sales representative, TSM, or open a request with support.

Sample
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N/A

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[appendix]
= Red Hat Subscriptions Overview

Three factors play an important part in selecting the right RHEL subscription:

* The (Service Level Agreement) SLA
* The number of (physical) Sockets and,
* The number of Virtual Machines.

Red Hat Enterprise Linux can have layered products, like clustering. These require a separate subscription.

== Service Level Agreement
An important part of a subscription is access to Red Hat support. The SLA associated with a subscription plays an important part for the customer here as this defines response times.

.Service level agreement response times
image::subscriptions/sla_response_time.png[pdfwidth=80%]

== Socket Pairs
A conventional RHEL subscription is based upon socket-pairs. A socket meant here is the _physical_ CPU socket.

Any subset of one or two sockets counts for one pair, so a node with 16 cores and two sockets requires one subscription to be compliant. A node with four sockets requires two single socket-pair subscriptions to be compliant.

A node with one socket will then require one subscription to be compliant, and a node with three sockets will require two subscriptions.

Of course, exceptions rule, so a node with four physical sockets of which only two have a seated CPU, will require just one subscription to be compliant.

== Virtualization
A conventional RHEL subscription can alternatively be used to subscribe RHEL virtual machines. The number of Virtual machines included with a subscription is two.

One subscription which would apply to a _physical_ dual socket machine can also be used for two Virtual Machines.  The number of virtual sockets or vCPUs assigned to the two Virtual Machines being subscribed by a conventional RHEL subscription are not relevant.

=== Virtual Datacenter Subscriptions
Virtual Datacenter (VDC) Subscriptions differ from conventional RHEL subscriptions in that they subscribe VMs per hypervisor rather than individually.

VDC subscriptions use a parent-child relationship to validate a VM's subscription: the parent (the hypervisor) consumes a subscription while the children (the VMs running on that particular hypervisor) "piggy back" on that subscription. Any supported RHEL VMs running on a hypervisor with a valid VDC subscription have a valid subscription.

Similar to conventional subscriptions, VDC subscriptions are applied to hypervisors per socket-pair. See <<Socket Pairs>>.


[NOTE]
====
A VDC subscription is only valid for the virtual machines running on a hypervisor, not for the hypervisor itself (the hypervisor must have a separate subscription for its own operating system).
====

== Layered products
Layered products require the same SLA and number of socket-pairs as the RHEL OS these products are deployed upon.

== Red Hat Enterprise Linux life cycle
.life cycle phases
image::subscriptions/lifecycle_phases.png[pdfwidth=80%]
The Life-cycle has different phases with different types of support. Depending on the applications, the deployment of nodes could be aligned with the different phases; deploy in Full Support, maintain in Maintenance Support 1 and replace in Maintenance Support 2 would be an ideal model.

.Life-cycle dates
image::subscriptions/lifecycle_dates.png[pdfwidth=80%]

The RHEL lifecycle can be found here: +
link:https://access.redhat.com/support/policy/updates/errata[]
