On November 3rd, Red Hat released its first stand-alone virtual infrastructure management solution called Red Hat Enterprise Virtualization Manager for Servers (RHEV-M). This product is offered separately from Red Hat Enterprise Linux (RHEL) and Red Hat Enterprise Linux Advanced Platform (RHEL-AP). It also includes a stand-alone hypervisor based on the KVM hypervisor code called Red Hat Enterprise Virtualization Hypervisor (RHEV-H).
It’s RHEV-H that I’d like to talk about. KVM depends on a Linux Kernel to operate – it is technically a type 2 hypervisor in that it adds virtualization capabilities to a host operating system. In RHEL and RHEL-AP, KVM is a kernel extension utilizing the RHEL kernel for process scheduling and resource management for VMs and native applications running directly on RHEL. RHEV-H incorporates a slimmed down just-enough-operating-system (JEOS) RHEL kernel that has been tuned specifically for VM scheduling and resource management.
Red Hat’s subscription policy for RHEL in virtual environments is OK, but not ideal such as Novell’s subscription policy that requires one SLES subscription per physical host allowing unlimited SLES guests regardless of hypervisor used. In the Burton Group report: “Virtualization Licensing and Support Lethargy: Curing the Disease That Stalls Virtualization Adoption” Chris Wolf illustrates that Red Hat requires customers to buy entitlements for RHEL running as a guest OS on a hypervisor such as VMware’s ESX or Microsoft’s Hyper-V. RHEL running as the Xen or KVM host hypervisor allows for 4 RHEL guests. Additional subscriptions must be purchased beyond 4. RHEL-AP as the Xen or KVM host allows for unlimited RHEL guests. This is similar to what Microsoft does with Windows Server licensing with Hyper-V. Prior to the RHEV release, customers had to contact Red Hat sales to purchase entitlements in packs of 10 guests. Red Hat has now formalized that with two SKU configurations: RHEL as a virtual guest 4-pack, and RHEL as a virtual guest unlimited.
With the release of RHEV-H, Red Hat could have created rules that favored running RHEV-H over competitive hypervisors, such as Hyper-V or VMware. However, they did not do so. RHEV-H is treated just like any other qualified third-party hypervisor if you decide to run RHEL guests on it. Yes, you are bound by the exact same rules whether it be RHEV-H, Microsoft Hyper-V, or VMware hypervisor that you choose to use (note: Red Hat has only qualified these hypervisors for running RHEL guests – XenServer, Novell SLES, and Oracle OVM are not included at this time). You must purchase RHEL guest entitlement packs. In addition, if you decide to use RHEL-AP, you are bound by its requirements whether it be RHEV-H or a qualified third-party hypervisor.
Red Hat, thanks for the example of fairness. Hopefully others like Oracle (see Chris Wolf’s blog from May 2009) will take heed.
[Posted by Richard Jones]