- What Is Extended Update Support (EUS)?
- Incorporating EUS Into Your Standard Operating Environment (SOE)
- Recommended Practices
- Base Channels and EUS Channels
- How to Access EUS
- What Is Included in and Excluded from EUS
- Additional Reading
What Is Extended Update Support (EUS)?
Extended Update Support (EUS) is an optional offering for Red Hat Enterprise Linux subscribers. With EUS, Red Hat commits to providing backports of Critical-impact security updates and urgent-priority bug fixes for minor releases of Red Hat Enterprise Linux, even for systems that are still one or two minor releases behind the current one. EUS enables customers to remain with the same minor release of Red Hat Enterprise Linux for up to approximately 24 months, allowing for extremely stable production environments for mission-critical applications.
With the introduction of the Red Hat Enterprise Linux 2013 Packaging Model, EUS is provided with Premium subscriptions and is available as an add-on for many others. Please contact your Red Hat Sales Representative if you unsure if you have access to EUS.
Incorporating EUS Into Your Standard Operating Environment (SOE)
The key benefits of EUS are that it:
- Helps to mitigate risk by providing a more restrictive selection of errata.
- Has an independent and more rigid release cadence than the standard Red Hat Enterprise Linux release cycle.
As a benefit of the independent release cycle of EUS releases, customers get the capability to skip specific Red Hat Enterprise Linux minor releases. Instead of having systems running every permutation of a major version of Red Hat Enterprise Linux in the environment (such as 6.1, 6.2, 6.3, et al), an organization can choose to release only specific minor releases of Red Hat Enterprise Linux. Depending on preference and scheduling of testing/validation resources, an organization can deploy every other minor release of Red Hat Enterprise Linux such as an "all-evens" or "all-odds" approach. The diagram below shows an example deployment use-case of EUS.
In this example, the organization wanted to deploy every third EUS release starting with 6.0.z (i.e., 6.0.z, 6.3.z, 6.6.z, et al). Additionally, they have an internal validation process that runs every one to six months that needs to be completed prior to releasing a minor release being delivered to their customers. In this example, by selecting every third EUS release, overlap between subsequent releases is allowed.
To obtain the maximum benefits from a Red Hat Enterprise Linux subscription, it is still the recommended practice for customers to upgrade to each minor release as we release it (e.g., 6.0 --> 6.1 --> 6.2).
This becomes an issue if:
- Customers have a policy of re-certifying application stacks when they move to new minor releases of Red Hat Enterprise Linux.
- Customers have sensitive workloads that they want to minimally disturb.
- Hardware vendors do not certify Red Hat Enterprise Linux minor releases as aggressively as needed by certain customers.
EUS provides a set of maintenance streams that:
- Last for 24 months instead of the normal six months (or 18 months, as in Red Hat Enterprise Linux 5 EUS).
- Minimize churn by being limited to Critical-impact security fixes and urgent-priority bug fixes.
EUS benefits IT organizations in that it:
- Reduces costs for running large Red Hat Enterprise Linux deployments.
- Reduces the amount of testing and re-validation customers need to do annually.
- Reduces the amount of change introduced into a customer's environment.
- Prevents an IT organization from having to support every minor release of Red Hat Enterprise Linux, which provides the flexibility to deploy every second or third Red Hat Enterprise Linux minor release as the basis of a Standard Operating Environment (SOE).
- Maintains continuity if an organization has applications that are only supported on a particular minor release.
- Optimizes the productive life of a deployed release if an organization has lengthy internal validation and certification processes that make it difficult to keep up with each minor release. This is common in many large organizations with shared IT departments that serve multiple business units. For example, EUS provides a means to put out an SOE based on Red Hat Enterprise Linux 6.2.z that moves 24 months later to an SOE based upon 6.6.z and then moves 24 months later to an SOE based upon the next appropriate .z release.
Base Channels and EUS Channels
Like all Red Hat Enterprise Linux maintenance, EUS is delivered via Red Hat Network, where it is implemented as a mirror channel hierarchy (separate base channels, one for each minor release, along with the relevant set of child channels). EUS can be activated for individual systems by subscribing them to the matching base channel.
The channel-naming scheme is derived from the main Red Hat Enterprise Linux channel hierarchy. Each minor release of a major Red Hat Enterprise Linux version has an associated EUS channel, and EUS channel version numbers always end with a z. In Red Hat Network, for example, the EUS channel associated with the release of Red Hat Enterprise Linux Server 6.5 (for the AMD64 architecture) is referred to as Red Hat Enterprise Linux EUS Server (v. 6.5.z for 64 -bit x86_64).
NOTE: The standard base channel (such as the Red Hat Enterprise Linux 6 channel) is mutually exclusive with any EUS channels (i.e., an individual system may only be subscribed to the standard base channel or to an EUS channel, but not to both simultaneously). Once a system has been subscribed to an EUS channel, it will receive only EUS errata updates. Refer to What Is Included in and Excluded from EUS for more information about EUS channel content.
Visit the Red Hat Network for more information regarding Red Hat Enterprise Linux subscriptions and base and child channels.
How to Access EUS
Customers with an active EUS subscription will see EUS channels in addition to the standard base channels in their Red Hat Network account. Only valid EUS channels are shown in Red Hat Network, meaning customers will only see the channels based on their particular system's hardware architecture and the major version of Red Hat Enterprise Linux that is installed. A system can be moved to an EUS channel by changing the base channel in that system's Channels menu to an EUS channel.
NOTE: Starting with Red Hat Enterprise Linux 5.1, customers can register systems directly to EUS channels. For system registration details, refer to the Red Hat Network documentation.
Upgrade Restrictions for EUS Channels
Customers who have systems subscribed to EUS channels should be aware that there are upgrade restrictions when upgrading between minor releases (i.e., systems subscribed to a certain EUS channel should always be upgraded to either a later, more recent EUS channel or to the base channel for that version of Red Hat Enterprise Linux). For example, if a system is currently subscribed to the EUS 6.1.z channel, at any time its subscription could be upgraded to:
- The 6.2.z EUS channel after the release of 6.2.
- The 6.3.z EUS channel after the release of 6.3.
- Any 6.y.z EUS channel where y is greater than 1.
- The standard base channel for Red Hat Enterprise Linux 6, which is the most recent minor release.
WARNING: It is unsafe to downgrade from a more recent minor release with a higher version number to an earlier minor release or an earlier EUS channel. For example, it would be unsafe to downgrade from Red Hat Enterprise Linux 6.5 to 6.4.z.
EUS Channel Deactivation
The 6.1.z channel, like all EUS channels, will be retired 24 months after it is created and becomes available on RHN. When an EUS channel reaches retirement, no new errata are released to the channels. However, all previously released errata remain available to customers with an active subscription. It is imperative to migrate to a later EUS release to continue receiving errata updates like security and bug-fix errata. You can check to see which EUS channels have been retired and are no longer receiving updates by looking at the Retired Channels page on RHN.
Automated reminder emails are sent 1-year, 6-months, 3-months, 1-month before, and the day of channel retirement. For an archive of all emails, refer to enterprise-watch-list mailing list.
What Is Included/Excluded from EUS
For approximately the first six months of its lifetime (until the next minor release), an EUS channel receives the same updates that the base channel receives. These include Critical, Important, and Moderate-impact security updates and urgent-priority bug fixes. Following the next minor release, an EUS channel is practically restricted to Critical-impact security advisories and selected urgent-priority bug fixes. For EUS subscribers, Red Hat will generally continue to proactively provide Critical-impact RHSAs independent of customer requests if and when available.
Not included in EUS updates are new features, hardware-enabling updates, or updated device drivers as EUS is intended to provide customers with a stable, long-term, secure environment. A list of EUS Inclusions is published here.
While EUS provides a more restrictive selection of errata, it does not provide an operational framework or discipline as to how a user of EUS can implement an errata management solution to support a rigid life cycle for their Red Hat Enterprise Linux systems. This is covered in the Red Hat Satellite Errata Management Guide.