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Server Virtualization Buying Guide -- Red Hat
VMware, Microsoft and Citrix are the big players in server virtualization, but if Red Hat has its way, the Big Three will soon be the Big Four.
The enterprise Linux maker has been hard at work developing its Red Hat Enterprise Virtualization (RHEV) Hypervisor, a bare metal hypervisor based on the company's Kernel-based Virtual Machine (KVM) virtualization technology. Last week it released RHEV 3.0 into productionafter a nearly six-month long beta.
RHEV uses the same hypervisor as the one that will be embedded in Red Hat Enterprise Linux 6.2. "With the new enhancements in RHEV 3, we are more closely aligned with VMware features-wise," Navin Thadani, Red Hat's senior director of virtualization, told ServerWatch.
The RHEV 3 purchasing proposition is very simple indeed: It is priced on a per-socket, per-year basis at $499 for a standard support package, and $749 for a premium support package. The RHEV Manager management system is included at no extra cost. That means RHEV could cost one seventh the amount of a similar VMware virtualization deployment in the first year; over three years, RHEV could cost about one third as much, according to Red Hat figures. These numbers must always be treated with caution, but if such cost savings are achievable, it certainly makes RHEV worth a closer look.
What you get for your money is a hypervisor that can support up to 160 cores and up to 2TB of RAM on the host machine, offering the potential to run hundreds of VMs on that host. The guest VMs -- running Windows or Linux -- can use up to 64 virtual CPUs and up to 512GB RAM per guest.
Other features include:
- Small footprint
- Intelligent failover
- Maintenance mode
- Live Migration
- Thin provisioning
- Processor hardware memory assist
- Memory overcommitment
Performance and security has been improved over the current RHEV 2.2 platform with several enhancements including:
- Moving the KVM networking stack from userspace into the Linux kernel, which improves performance and reduces latency.
- A new feature called transparent huge pages, where the Linux kernel dynamically creates large memory pages (2MB versus 4KB) for virtual machines, improving performance for most workloads by reducing the number of times that memory is accessed.
- The use of SELinux-based sVirt infrastructure for what Red Hat terms "military-grade" hardening of the hypervisor
RHEV Manager has also been completely updated. Previously, the management system ran on a Windows system with a SQL Server backend, but it is now a JBoss application with a PostgreSQL database that runs on Red Hat Enterprise Linux. Authentication no longer must be carried out using Active Directory. It can use LDAP instead. "The hypervisor in RHEV was always open source, but until RHEV 3 the management system wasn't, said Thadani. "Now that it is all open source, it will have huge appeal for many organizations."
There is a growing trend for many organizations to use more than one hypervisor, which is something Red Hat may well benefit from in terms of wider adoption of RHEV. That begs the question of how these multiple hypervisors can be managed. Thadani said he believes administrators will be quite happy using multiple management systems as well. "Virtualization is getting better understood, so if an admin uses [VMware's] vCenter then it won't take a lot to deploy RHEV. The concepts are the same."
RHEV Manager also has a RESTful API, which makes it possible to manage RHEV using third-party products as well. "I do believe that there will be higher-level systems running on top of vCenter and so on," said Thadani. "As long as the API offers everything that the GUI can do, and more in the case of RHEV, then administrators can use a management system that sits on top."
RHEV3.0 also includes a free "power user portal" that provides developers and other IT staff with a self-service interface that allows them to provision virtual machines, define templates and administer their own environments.
For smaller businesses that lack the resources to implement a full-blown SAN it is now possible to deploy RHEV on a host with local disk storage only, although when implemented in this way, it is not possible to use some of the more advanced KVM features that rely on shared storage like live migration
This could change, however, due to Red Hat's acquisition of the open source storage company Gluster. An equivalent to VMware's Live Storage Migration has not yet been implemented into RHEV, but Thadani said that this has been implemented upstream, and it is scheduled for introduction with RHEV's next release.
As well as the pricing mentioned above, RHEV is also available as a RHEV for Servers Starter Kit for $2,994 per year (standard subscription) or $4,494 per year (premium subscription.) This includes six managed sockets and management software -- enough to manage a virtualization environment with three dual-socket hypervisor hosts.
RHEV 3 Supported Architecture and Guests
Hypervisor hosts require 64-bit processors supporting Intel V or AMD-V virtualization technology. RHEV 3 supported guests include, RHEL3, RHEL4, RHEL5, RHEL6, Windows 2003, Windows 2008, Windows XP and Windows 7.
Paul Rubens is a journalist based in Marlow on Thames, England. He has been programming, tinkering and generally sitting in front of computer screens since his first encounter with a DEC PDP-11 in 1979.
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