Submitted by Ondřej S, 10 December, 2009 - 12:03

We have some new information about Red Hat Enterprise Virtualization or RHEV, which has been released by Red Hat recently.

• KVM, which serves as a foundation for Red Hat Enterprise Virtualization, has been already included in RHEL 5.4. Although originally meant as unsupported "technology preview" only, in RHEL 5.4 it has been released with production-ready status and is fully supported. Our experience with KVM is good so far, it's stable and suprisingly well performing.

• RHEV requires virtualization assistance from the hardware. Intel VT-d, AMD-V and 64bit architecture are neccessary. Unlike with older virtualization software, don't expect it to run on old hardware. The benefits of hardware virtualization are so significant that this requirement is perfectly rational. (Tip: how do I find whether hardware virtualization is possible on my hardware?)

• A funny thing: Red Hat claims that under certain conditions, the RHEV virtualization can make better use of the modern hardware (eg. Intel Nehalem architecture) than a bare-metal operating system. This could lead to surprising results. You could get more than 100% performance of the original bare-metal system if you virtualize certain specific applications. LAMP is named as one example. That is very interesting. (Source.) Before you say that it's physically not possible, let me say that in fact it's not RHEV that is being so fast. It's the application that is so inefficient on a modern hardware, that you can actually benefit from scale-out tactic by deploying several smaller VMs and load-balancing the requests between them, rather than scaling up the resources.

• The biggest controversy will be around using some of the Microsoft technologies. RHEV Manager (RHEV-M) runs on top of Windows Server 2003. It is because Red Hat has gained access to some technologies used within RHEV by acquring a company named Qumranet with their Window-based VDI product. (Let me say it again to make it clear: only the management UI runs on Microsoft. The hypervisors themselves run Linux, either full RHEL or stripped-down RHEV-H.)

• Red Hat announced its intention to migrate the management UI away from Windows. The new system is supposed to be built around JBoss and Hibernate. Red Hat asks customers to temporarily tolerate current. They should see the management system as a black-box, concentrating on the job it does, rather than an OS it uses. It sounds logical. Releasing a stable version as soon as possible is much more important than investing additional months or years of development into a brand new Linux-based management system. The market moves really fast and the competition doesn't wait.

• Unfortunately you need a Microsoft Internet Explorer to access the management console. This bothers me much more than the management system running on Windows. I hope this will be the first feature on a change list with a new release. Lot of techies are simply not comfortable with MSIE.

• Contrary to what I previously thought, RHEV M is not based on oVirt project. RHEV M is rather an adaptation of Qumranet's VDI management for Windows, whilst oVirt is an open source management toolset built on Linux. My opinion is that oVirt was more of a proof-of-concept and an inspiration for RHEV M. Maybe it will serve as a foundation to building RHEV M on Linux. Update Dec/11 2009: Andy Cathrow from Red Hat has stated that oVirt will stay here as a "incubator" for further development of virtualization technologies, and pointed to project named Deltacloud, which is being build around oVirt.

• Xen uses a very modified kernel (which has compatibility and certifications consequences), while KVM is a set of simple and clean kernel modules. The implication is that if an application has been successfully tested (and certified) on a bare-metal RHEL, it will run (and stay certified) even in KVM-virtualized RHEL. Red Hat says the binary compatibility is guaranteed. (How will Oracle respond?)

• Red Hat Enterprise Virtualization is available through partners that have passed a training, because the product is very complex both technically and in licensing. It is necessary that it is represented by qualified people. For the same reason, no public evaluation version is available, you have to ask a partner. (Advertisement: Enlogit has been trained. If you need help, let us know.)

• RHEV S is already in an official price list. The price is very friendly compared to a competition, which should lead to RHEV being a serious competitor to the main targets, namely VMware vSphere and Microsoft Hyper-V.

• RHEV Hypervisor, which is a stripped-down version of RHEL, is a part of Red Hat Enterprise Virtualization license (or a subscription, because RHEV sticks to the Red Hat's dedication to subscriptions rather to licenses). Other option is to buy (to subscribe) to a RHEV and have appropriate RHEL operating system subscriptions on the physical servers. The fully-featured RHELs can also serve as hypervisors. This way, you already have licensed guest VMs running RHELs. There is many licensing tactics suiting different scenarios. If you are in doubt, ask Enlogit for help.

Update Feb/3 2010: see our blogpost RHEV abreviations explained.

Ondrej Suchy is a CEO and founder of Enlogit, an IT solution and services provider with strong skills in Linux and open source. Ondrej has a Bachelors degree in Software engineering and economy from Czech Technical University. He is an user and fan of open source since 1997. Have question? Contact me

Ondřej S's blog