December 05, 2012, 10:30 AM — Less than a year after a major update to its Red Hat Enterprise Virtualization (RHEV) package, Red Hat has upgraded the software to offer more advanced storage capabilities.
Released Wednesday, RHEV 3.1 allows administrators to make snapshots and clones of running virtual machines. And, in a technical preview mode, RHEV 3.1 supports storage migration for virtual machines (VMs), in which the backup disk image of a running VM can be moved from one SAN (storage area network) to another without stopping the running VM, said Chuck Dubuque, Red Hat product marketing senior manager for Red Hat virtualization infrastructure.
Storage live migration can be useful for several areas, Dubuque said. Live storage migration can be useful for balancing I/O across a system, or for those cases when a pool of VMs need to move from one SAN to another. In previous versions of the RHEV, such migrations would require the live running VM to be shut down while its disk image was being relocated. The live migration technology is available as a technology preview, until the release of the next version of Red Hat's flagship RHEL (Red Hat Enterprise Linux), which will provide the last bit of the needed functionality to fully execute live migrations.
With snapshots, RHEV can save a copy of a running VM for record-keeping purposes. And with cloning, RHEV can make a copy of a live VM that will also be operational. Previous versions of RHEV could only do snapshots and clones of a VM after that VM had been shut down. Snapshots are particularly valuable in development environments, in which the software being written must frequently be tested for bugs.
Dubuque noted that the KVM (Kernel Based Virtualization) hypervisor -- which is the open source foundation for RHEV -- has supported both snapshots and cloning, but noted that the functionality wasn't very robust. "Part of the value that Red Hat adds is hardening existing technology for enterprise use," he said.