Interview: Red Hat on Red Hat Enterprise Virtualization

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Red Hat released Red Hat Enterprise Virtualization for Servers on November 3rd. A couple of weeks before the release, I emailed Red Hat media relations contact Kerrin Catallozzi and asked for an interview with some Red Hat employees regarding Red Hat Enteprise Virtualization.

It took a several weeks to get the answers back mainly because the official product release happened... and after I had the chance to download, print and read the documentation, most of my questions had been answered... and I ended up coming up with all new questions. Kerrin found Andy Cathrow (Product Marketing Manager) and Jim Brennan (Senior Product Marketing Manager) of Red Hat to provide the answers. Andy Cathrow will be referred to as "AC" and Jim Brennan will be referred to as "JB".


Jim BrennanJim Brennan serves as Senior Product Marketing Manager for Desktop Virtualization at Red Hat. He is responsible for the market strategy and positioning of Red Hat Enterprise Virtualization for Desktops. Jim has over 12 years of experience in the development, management, and marketing of technology products.

Prior to joining Red Hat, Jim spent eight years with Internet Security Systems (now part of IBM), where he held positions in research and development, product management, and product marketing for various information security products and technologies.

Andy CathrowAndy Cathrow serves as Product Marketing Manager at Red Hat and is responsible for Red Hat's virtualization products. Andrew has also managed Red Hat's sales engineers.

Prior to joining Red Hat in 2006, Andy worked in product management for a configuration company, and also for a software company that developed middleware and messaging mainframe and midrange systems. Earlier in his career, Andrew held various positions at IBM Global Services.

[Update: - Dec. 9, 2009 - I got a chance to chat with Andy and Jim in real-time and ask several additional questions at the Red Hat Virtual Experience 2009 online conference. See the comment below the main interview for a transcript.]

General Questions

ML: I must say that RHEV is very competitively priced. You currently offer Academic pricing on the RHEL product line. Any plans to offer Academic pricing for RHEV?

AC: We have not announced academic pricing but it's certainly under consideration based on demand.

ML: I understand that the product that RHEV for Servers evolved from was SolidICE from Qumranet and developed originally outside of the influence of Red Hat. The management application from SolidICE was heavily based on Microsoft technology and I'm sure the desire to get the product to market as soon as possible to meet your customer's needs meant that you just couldn't totally scrap the Windows-based design of the management application. In the year between the merger with Qumranet and the release of RHEV for Servers, what were the primary changes made to the product?

AC: We made many, significant changes. A quick, but not complete list includes:

  • SAN support - including iSCSI and Fiber channel (previously NFS only)
  • Multipath I/O
  • NIC bonding (host)
  • Multiple nics (guest)
  • VLANs
  • High availability
  • System scheduler (distribution policies, scheduling VMS)
  • Power Saver
  • Support for large hosts 96 cores, 1TB RAM
  • Support for large guests 16 cores, 256GB RAM
  • Support for managing hosts - including configuration files and software updates

ML: I heard that there is a development effort under way to make the management application be multi-platform by writing it in Java via JBoss and Hibernate with a database abstraction layer where perhaps several different databases will be supported. Is that true and if so, how is that progressing and when do you expect to enter general availability?

AC: We haven't announced our plans for database support, however use of JBoss and Hibernate will offer us that flexibility. The choice of supported platforms will be based on customer demand and on QA resources.

ML: If and when a multi-platform version of the Management application becomes available, how will that impact the existing Microsoft-based system? Will both continue to be supported into the foreseeable future or will the initial release be phased out in favor of the multi-platform solution?

AC: New development will be focused on the cross platform release. While we continue to offer bug fixes and security errata on previous releases new functionality will only be available in the cross platform release.

ML: The Spice protocol is patented. Are there plans to put the Spice patent(s) into the free software patent pool?

JB: No such plans have been announced, but Red Hat will be looking at various options when it comes to how we bring the SPICE protocol to market in a way that benefits both customers and partners alike.

Technical Questions

ML: On page 100 of the RHEV for Servers 2.1 Administration Guide, in section 6.2. Creating New Virtual Machines it talks about the two ways of creating a virtual machine: 1) From a blank template, and 2) From an existing template. Then referring to existing templates it says, "This is currently not recommended as the best way of creating virtual servers, as it can significantly downgrade the performance of the platform." What does that mean exactly and is this a long term issue or one you expect to have resolved in the near future?

AC: An early release of Red Hat Enterprise Virtualization with QCOW2 disk format exhibited a larger overhead than expected. We've since rectified that issue and now QCOW2 performance is within a couple of % of RAW files. Note: This issue was only experienced during installation.

ML: In RHEV for Servers there are two types of display protocols for virtual machines, VNC and Spice. In the screen captures I've seen in the documentation, machines that have "desktop" as part of the name show as using the Spice protocol whereas other machines are typically set to the VNC protocol. Is this choice mainly so the client side has the convenience of falling back to VNC if Spice is not available to them or are there differences in the protocols that would make VNC more appropriate for one type of virtual machine and Spice more appropriate for another?

AC: VNC is our default protocol for servers, where we don't need the added functionality of SPICE. SPICE works with and without guest side drivers. Without drivers in the guest it acts as a simple display device, with drivers it supports full acceleration. While SPICE can be used for servers we typically use VNC.

ML: Does RHEV for Servers come with any tools to resize the disks/partitions used by virtual machines?

AC: We have the ability to grow VM storage and support thin provisioning.

ML: On page 3 of the RHEV Hypervisor Deployment Guide (5.4-2.1) it mentions that the RHEV Hypervisor is derived from the oVirt Node project. I know that oVirt is primarily sponsored by Red Hat and developed by Red Hat employees. With the release of RHEV what is the status of the oVirt project? Is this a change from the what Qumranet was using in the SolidICE product prior to merging with Red Hat?

AC: The oVirt project remains an important project for Red Hat, acting as an incubator for open source virtualization technologies. In addition to the oVirt node's inclusion in Red Hat Enterprise Virtualization, the oVirt server suite project has spawned the Deltacloud project.

ML: On page 6 of the RHEV Hypervisor Deployment Guide (5.4-2.1) it says that at least 750MB of storage are required for installing the Hypervisor to USB or internal hard disk. I recall some previous statements that the Hypervisor would be much smaller and on the order of 100MB. Am I mistaken about that or do you hope to reduce the deployment size of the Hypervisor in future releases?

AC: The Red Hat Enterprise Virtualization image is less than 100MB. The extra storage is used at runtime for log files, swap space and any transient storage - for example when uploading ISOs to the ISO library. This can all be on SAN or local disk.

RHEV for Desktops

ML: You decided to release RHEV for Servers before RHEV for Desktops. That seems a little backwards considering that Qumranet's SolidICE product was primarily aimed at Desktops. Are there technical reasons RHEV for Desktops has not been released yet or was the staggered release schedule chosen for marketing and customer support reasons?

JB: Red Hat Enterprise Virtualization for Servers was brought to market first as a function of the fact that Red Hat has been in the server virtualization market for over two years, and customers were in need of more comprehensive management tools. The desktop virtualization market is just now beginning to take shape, with most production deployments not planned until 2010. It therefore seemed most prudent to focus first on the server market, followed shortly thereafter by a desktop release.

ML: Will RHEV for Desktops be an add-on package compatible with the current management server where the same management server can handle either or both Server and Desktop?

JB: Yes, customers will be able to manage both servers and desktops from the management console.

ML: One could certainly run virtual desktop VMs with the current RHEV for Servers product. What are the primary differences between RHEV for Servers and RHEV for Desktops that justify having the two as separate products?

JB: In addition to the functionality contained within Red Hat Enterprise Virtualization for Servers, Red Hat Enterprise Virtualization for Desktops will contain the connection broker and user portal needed to facilitate connections between users and their virtual desktops. Red Hat Enterprise Virtualization for Desktops will also offer the ability to create pools of on-demand virtual desktops.

ML: What thin-client hardware is compatible with RHEV for Desktops?

JB: Red Hat is in the process of certifying a variety of thin client models from all of the major manufacturers. A complete listing will be available when Red Hat Enterprise Virtualization for Desktops releases.


I'd like to thank Kerrin Catallozzi, Andy Cathrow and Jim Brennan from Red Hat for taking the time to indulge a rather small Linux oriented website with an interview. Thanks guys!

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Scott Dowdle's picture

Red Hat Virtual Experience 2009

I attended the online "Red Hat Virtual Experience 2009" conference today and was able to hear talks on various Red Hat, RHEL, and RHEV topics. It was fantastic.

I was able to chat with Andy Cathrow and Jim Brennan in realtime and asked the following questions and got the following answers:

ML: In the upcoming RHEV for Desktops, will there be any type of disk image management features that helps with persistant data (layering of individual user personalizations for example) or is it primarily for non-persistent, "shared" type disk images?

AC: It supports both stateful and stateless desktops... so you could have a pool of "blank" images that have the basic applications and when the user logs on they get their user profiles, drivers mapped etc. When they log off the image "rolls back". Or you could have persistent VMs for users that maintain all their data and applications. We use snapshots on top of a base image to do this and reduce disk utilization.

ML: Does the RHEV management software offer processor usage management features so you can control how much CPU a VM can use so one or more with CPU intensive jobs don't use more CPU than desired.. other than simply setting the number of CPUs a VM has access too? I've heard that with cgroups scheduling features in the kernel it is technically possible.

AC: RHEV is using KVM in RHEL 5, where we backported KVM into 2.6.18. With a rhel6 based hypervisor we'll get the new CFS scheduler and features like cgroupsw which allow a more fine grained control of virtual machine resources.

ML: Do you consider Virtual Bridges' VERGE technology (formerly Win4Lin and used in IBM's SmartWork product) and remote display protocol real competition to the SPICE protocol offered in RHEV?

AC: For display protocols there's ICA, RDP and VNC Today (before SPICE). I'm not sure what they are using , but with respect to use experience (graphics, multi-monitor, etc) I'd be surprised if it's superior to spice.

JB: Different architecture Scott. SPICE is comprised of components that reside on the host, the client, and from within the VM itself. Makes it possible to offload processing to the client, therefore conserving resources on the host.

ML: Given the architecture of SPICE and its integration into RHEV, do you anticipate it would be hard to separate out as a separate client / server app in non-virtualized environments? It sounds like a clear winner (alternatives to ICA, RDP, and VNC) given its performance.

AC:: We've opened the protocol and the code today so it certainly could be used by other hypervisor vendors, even outside of virtualization - eg. as a remote protocol for accessing physical servers (eg, think X-Spice?). The great news here is that it's not tied to one vendor, now everyone from hypervisors vendors, to thin client vendors can extend the protocol and move it forward.

ML: Yes, open source products do empower their users. Thanks.

AC: We've got a yum repo along with the source and docs at right now if you want to try!

ML: Thanks for the reminder. When I first saw mentioned either I got the spelling wrong or it wasn't up yet... and I hadn't been back. Now I have a lot more content to consume on the subject. :)

AC: Yep - is up now. Spice isn't in qemu today, so it's built as a standalone component but we're working to get it in qemu-kvm.

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