Microsoft at a virtualization product launch gave a long-delayed demo of Hyper-V live migration. In showing the upcoming capability to a crowd of customers in Bellevue, WA, Bob Muglia, senior VP of Microsoft's server and tools business, suggested that in the Windows Server product which follows Windows Server 2008, users will be able to instantly migrate virtualized software deployments from one server to the next, for consolidation on the fly.
Without mentioning a specific time, Microsoft stated live migration would be ready for Windows Server 2008 R2, which it touted as the very next version of the server operating system. Yet this product roadmap updated last month clearly marks the R2 version as “scheduled for release during 2010.”
Live migration may actually be a necessity for some data centers, especially for systems that use failover clustering. If a virtual machine is running on a system that fails, conceivably a former state of that machine could be restored from a backup, but that would take time. With live migration, data centers can relocate running instances of critical servers between physical processors, with zero downtime.
In the absence of live migration, this year, Microsoft had been trying to promote an alternative scheme it calls quick migration, not only as a substitute but possibly -- if you follow the logic -- something even better. “Using Windows Server Hyper-V and the quick migration capability,” reads a January 2008 Microsoft white paper, “you can consolidate physical servers and, at the same time, maintain the availability and flexibility of business-critical services during scheduled maintenance, or quickly restore services after unplanned downtime.”
“Without live migration, any migration solution still involves downtime, and therefore can't really compete with VMotion. Host-level clustering is great, and something I'd love to see VMware tackle for those shops where VMware HA just isn't quite enough to meet SLAs [service-level agreements],” wrote IT administrator Scott Lowe in July 2007. “But host-level clustering is no substitution for VMotion.”