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RHEV 3.1 to bring storage live migration, scalability

RHEV 3.1 will include storage live migration and other KVM virtualization management features that will give server virtualization users a viable alternative to Microsoft and VMware.

On the heels of virtualization management licensing news from Microsoft, another competitor plans to strike out at VMware. The increasing competition stands to benefit IT pros that will have more viable server virtualization options.

Red Hat Inc. made version 3.0 of its virtualization management product generally available on Wednesday with better scalability -- though not as much as expected. The company also revealed new details on what the company has up its sleeve for the rest of 2012 -- a RHEV 3.1 release that will add better storage support.

Coming soon: storage live migration

Features planned for RHEV-M 3.1 show Red Hat is serious about catching up with its chief competitor.

Storage, for example, is a key focus of the upstream release, which is slated to include basic functions like the ability to hot plug and unplug disks and create live snapshots of virtual machines from a guest agent capable of quiescing the file system. The ability to dynamically resize guest and host storage and storage live migration are also scheduled for this release.

Another feature due out with version 3.1 is the ability to allow a VM to use disks from multiple storage domains or pools, which is "especially important if you have tiered storage," according to Andrew Cathrow, a product manager for Red Hat.

This is important if you have any kind of storage, according to Ryan Murray, director of infrastructure for Ganart Technologies, based in Carrollton, Texas. "Right now, a virtual system can only attach to one storage domain. So, if I run out of space on that one storage domain, I have to migrate that to another storage domain, because I can't add a slice from another one."

Other new storage features coming in RHEV 3.1 are "floating" disks, which are not associated to a particular VM and support for alternative shared file systems such as Gluster or IBM's GPFS.

New networking features due in RHEV 3.1 include the ability to designate different networks for management, storage and VM traffic, UI support for Cisco UCS and the ability to hot plug and unplug NICs.

The last vestiges of Windows requirements for RHEV are supposed to vanish in 3.1 with full support for Web Admin, a purely HTML-based Web client that does not require Microsoft Internet Explorer.

RHEV-H 3.1  adds scalability

RHEV-H 3.1 will be based on Red Hat Enterprise Linux (RHEL) 6.3, which confers better performance and scalability, as well as new features.

Scalability turned out to be a tricky issue with Wednesday's release of RHEV 3.0. As of the beta release last August, Red Hat's marketing touted a maximum of 64 virtual CPUs and 2 TB of RAM per guest, but with the GA announcement, that RAM limit was reduced to 512 GB.

With 2 TB support, RHEV would have doubled the RAM support offered in VMware's vSphere 5. Instead, the GA version of RHEV 3.0 will ship with half the memory support for large VMs that its rival can boast.

According to Red Hat, the 2 TB in beta was just a theoretical limit.

"RHEL 6.2 wasn't out at that point, and [once RHEL 6.2 came out] the host was only certified for 2 terabytes RAM on the host itself," Cathrow said. "RHEL can do more and we have tested VMs up to 3.5 terabytes, but 2 terabytes is the biggest hardware that's really shipping."

With RHEL 6.3 support, Red Hat expects more than 2 terabytes to become available for the host.

Ultimately, these numbers are more marketing posturing than anything of meaning to users. "In an enterprise, certain types of servers are not good candidates for virtualization," said Murray. "A system that you're going to run that much RAM on… you would want it on bare metal."

RHEV 3.0 ditches Microsoft

While customers await the .1 release, RHEV 3.0 is available now.

In this release, Red Hat gives Windows the boot. RHEV-M had been based on a Microsoft .NET and SQL back end. That's been replaced with a Java code base and PostgreSQL.

It's not just tribalism that had users anxious to see this happen, according to Ganart Technologies' Murray. "Pre 3.0, a lot of the problems and a lot of the issues I had were related to the Windows node, and that's not just an anti-Windows statement."

Previously, issuing commands from a Windows-based RHEV-M system to a Linux-based KVM hypervisor required custom code for translation. Moving RHEV-M to a Linux system makes issuing a command "as easy as sending the request over," he said.

"This is a real turning point in the management and the maturity of KVM," said Gary Chen, an enterprise virtualization software analyst for IDC. "I think this is going to be a really foundational piece that they're going to build on with dot-releases."

Expect to see those dot-releases arrive on an aggressive schedule, he added.

The challenge still facing Red Hat is in continuing to build partnerships with other vendors to support RHEV, Chen said. "Vendors right now are trying to prioritize what they're going to support. I think it will be important for Red Hat to kind of get higher on that priority list."

Beth Pariseau is a senior news writer for Write to her at

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