Oracle Linux : Frequently Asked Questions (FAQs)
This article contains the answers to a number of questions I've been asked about Oracle Linux since its introduction. The answers are backed up by quotes and links where possible, but they also include some of my personal opinions as well, so don't assume Oracle agree with everything I say here.
- What is Oracle Linux?
- How much does Oracle Linux cost?
- How does Oracle make money from Oracle Linux?
- Are there any hardware restrictions for Oracle Linux?
- Why do vendors sometimes give us conflicting messages about Oracle Linux pricing and hardware support?
- What versions of Linux do Oracle support their products (Database, WebLogic etc.) on?
- Will Oracle ever break the Binary Compatibility of Oracle Linux?
- What if Oracle change their pricing model?
- What is the Unbreakable Linux Kernel (UEK)?
- Is switching the kernels difficult?
- What is Red Hat Enterprise Linux (RHEL)?
- What do you get when you buy a RHEL subscription?
- How do I switch from CentOS to Oracle Linux?
What is Oracle Linux?
Oracle Linux, like CentOS and Scientific Linux, is a binary clone of the Red Hat Enterprise Linux (RHEL) distribution. In this relationship Red Hat is known as the upstream vendor. What does this mean? These groups download the RHEL source code, remove trademarks, compile it, create a distribution and allow you to downloads and use it for free. This is perfectly legal because the software that makes up this Linux distribution is covered by an assortment of open source software licences, including GPL. Indeed, without the these open source software licenses RHEL would not exist as it is the reason Red Hat can legally create their distribution, since they are not the originators of all of this code.
How much does Oracle Linux cost?
Nothing! It's free!
Like CentOS and Scientific Linux, but unlike RHEL, Oracle linux allows you to do the following for free:
- Download the ISO images of the binary distribution (yum.oracle.com or edelivery.oracle.com).
- Download and apply bug fixes (errata) to your installations using Yum and DNF in the normal way. If you are not paying for support, the upgrades come from here (yum.oracle.com).
The pricing model is presented in this document:
I draw your attention to the "What is Oracle Linux?" section, where it states,
"Unlike many other commercial Linux distributions, Oracle Linux is easy to download and completely free to use, distribute, and update. Oracle Linux is available under the GNU General Public License (GPLv2)."
How does Oracle make money from Oracle Linux?
You can choose to pay for a support subscription if you want, but it is optional. Depending on the level of support you choose, this can include the following additional benefits.
- Full indemnification against intellectual property claims
- Ability to raise SRs
- Oracle Enterprise Manager 12c and Ops Center for Linux Management included
- Ksplice - For zero downtime updates
- XFS support
- Support for all VMs or Oracle Linux-based Docker images running on the box.
You can see a full list of benefits here.
In over a decade of using Red Hat Linux distributions I have raised 2 support calls against the OS. In both cases the issues were fixed in errata, triggered by the code developers themselves, not by my calls.
Are there any hardware restrictions for Oracle Linux?
There are no extra hardware restrictions for Oracle Linux compared the RHEL. Just to confirm this, here is a quote from the Oracle website.
"Oracle Linux support for Oracle Linux running with the Red Hat compatible kernel is available for all hardware systems considered certified or compatible for the corresponding release (e.g. Oracle Linux 5 Update 7 corresponds with Red Hat Enterprise Linux 5 Update 7) of Red Hat Enterprise Linux according to the Red Hat hardware catalog"
A list of certified servers is available here.
So whatever RHEL support, Oracle Linux will support. Is running Oracle Linux inside VMware VMs supported? Yes. You can see the certification here.
Why do vendors sometimes give us conflicting messages about Oracle Linux pricing and hardware support?
In *my opinion*, there are two main reasons for this:
- They are ignorant of the facts. All this information is freely available from the Oracle web site.
- They have their own agendas. In many cases, selecting Oracle Linux means they will not get a kickback from Red Hat for selling you the subscriptions. Red Hat's motivation for spreading fear, uncertainty and doubt (FUD) is a little more obvious as Oracle Linux impacts on their subscription revenues.
What versions of Linux do Oracle support their products (Database, WebLogic etc.) on?
Oracle only supports their enterprise products on 3-4 versions of Linux.
- Oracle Linux
- Red Hat Enterprise Linux (RHEL)
- SUSE (SLES)
- Asian Linux (Asianux) - Only some products.
Oracle products will run on numerous other versions of Linux, but they are not supported, so you can't use them. If you need any more proof of this, check out the certification matrix on MOS (https://support.oracle.com).
By all means choose alternatives, like CentOS or Scientific Linux, for servers not running Oracle software.
Will Oracle ever break the Binary Compatibility of Oracle Linux?
This question has been raised more times than I care to remember. Suggesting Oracle will break binary compatibility is complete nonsense. Oracle have said from day 1 that they *guarantee* binary compatibility of Oracle Linux. It is compiled from the RHEL source code. They have no intention of breaking this because it would make their life, and that of every other software vendor, miserable. Think of what it would actually mean. They would break their own products on this distribution. Here’s a quote from an Oracle whitepaper on the subject.
"Oracle Products are built on Oracle Linux and because of the binary compatibility between Oracle Linux and RHEL, Oracle doesn’t run additional tests on RHEL, but simply paper certifies the same binaries built. If customers have an application deployed on Red Hat Enterprise Linux, it will continue to run as-is on Oracle Linux. From a software vendor and a hardware vendor point of view, Oracle certifies and supports all the applications that are certified on Red Hat Enterprise Linux" (http://www.oracle.com/us/technologies/027614.pdf (no longer available))
A similar statement is available from here also.
"Oracle will offer support for the operating system running underneath any ISV application that has been certified for use with Red Hat Enterprise Linux. An ISV does not need to do anything special to test and certify their application with Oracle Linux. Going forward, ISVs may test and certify Oracle Linux by running the same tests they run against RHEL." (http://www.oracle.com/us/technologies/027617.pdf)
If anything, running RHEL is the most risky option since Oracle can refuse to certify their products on this distribution. Oracle develops their products on Oracle Linux, then certify on RHEL and port to other UNIX flavors. We saw an issue recently where support for Oracle Linux 6 was announced and it was about 90 days later that support for RHEL6 was announced. Since we are running Oracle products, which version of Linux do you think is more risky? One produced and used by Oracle, or one from another vendor?
What if Oracle change their pricing model?
What if Red Hat do? What if any other vendor you use changes their pricing model? The solution is simple. You pay for the subscription or move to another vendor, like Red Hat.
Realistically you have a choice of Oracle Linux (free) or RHEL (not-free). The backout plan for whichever one you chose is to switch to the other. That’s it!
Remember, CentOS and Scientific Linux, both of which are clones of RHEL (like Oracle Linux), are not supported by Oracle for the database and WebLogic installations, so you CAN NOT use these. You can happily use them for non-Oracle installations though.
CentOS is similar to Oracle Linux. Free to use, but you can choose to pay for support.
What is the Unbreakable Linux Kernel (UEK)?
The Linux kernel is the heart of the Linux operating system. Depending on the version you are using, this is a 27M binary that does a lot of the important low-level stuff in the operating system. In addition to providing the Red Hat compatible kernel, Oracle Linux includes UEK, which is closer to the mainline kernel and in my opinion better for running Oracle products. It is your choice if you use this kernel or the Red Hat compatible kernel.
To put this into context, Oracle Linux 6.3 contains 3.7Gig of binary packages. Of that, just this optional 27M package and about 100M of support packages are provided in addition to the RHEL distribution software.
The UEK is probably the most misunderstood aspect of Oracle Linux and one of the prime things people latch on to, when trying to "prove" RHEL is a better choice than Oracle Linux. UEK should be your preference when using Oracle Linux as the basis for other Oracle products. Choosing to not use it is like choosing to cripple Linux.
VMware fully supports UEK, as can be seen here (UEK2, UEK3, UEK4 etc.).
It is also worth noting that regular applications don't talk directly to the Linux kernel, so substituting UEK3 or UEK4 for the Red Hat compatible kernel is not going to break applications.
Is switching the kernels difficult?
No! The newer updates of Oracle Linux 5 and 6 use UEK by default, as does OracleLinux 7, but still have the Red Hat compatible kernel installed. If you need to switch to the Red Hat compatible kernel for any reason you can do this in one of two ways.
- One-Off : During server boot, hit a key to enter the GRUB menu. Use the arrow keys to select the kernel of interest from the list and hit the "Enter" key to boot using that kernel. This is not a permanently change. The next reboot will start up with the default kernel unless you intercept it again.
- Permanent : Edit the "/boot/grub/grub.conf" file and reboot, as described here. This will persist the kernel selection between reboots.
If you want to permanently remove the Red Hat Compatibility Kernel (RHCK) you can using the kernel-transition package, as described in MOS Note (Doc ID 2217498.1).
What is Red Hat Enterprise Linux (RHEL)?
RHEL is a Linux Distribution. It is a collection of open source software written by an extremely wide variety of people, employed by an equally wide variety of companies. Software contributors to Linux, and therefore the RHEL distribution, include very large companies including Intel, IBM, Google, Samsung and Oracle, in addition to the well known contributors such as Red Hat, SUSE and Canonical (of Ubuntu fame). Even Microsoft contribute to the Linux kernel, to enable compatibility with Hyper-V.
The important point to remember here is the software making up the whole RHEL distribution is not the property of Red Hat. It is merely an aggregation of many other peoples work, along with their own.
Being open source, anyone is legally entitled to take the source code of any Linux distribution, including Red Hat, and do what they want with it, including compiling it and selling support for the product.
What do you get when you buy a RHEL subscription?
You are legally entitled to all the source code of RHEL for free. If you want you can download it, compile it, create your own distribution and use it all for free. So what are you paying for?
- The right to download the ISO images of the binary distribution.
- The right to download bug fixes (errata) and apply them to your installations.
- The right to raise bugs and get support from RH support.
Notice, you are not buying a license in the conventional sense. You are buying a support subscription.
How do I switch from CentOS to Oracle Linux?
Now that CentOS is being discontinued, you might want to switch from CentOS to another RHEL clone. It;s really easy to switch from CentOS to Oracle Linux, as described here.
For more information see:
Hope this helps. Regards Tim...