Virtualising a data centre can make it more flexible, but it also introduces new points of failure and it doesn't remove the need for critical servers to be duplicated for fail-over, disaster recovery (DR) specialist Neverfail has warned.

The warning came as replication and DR companies lined up to promise support for Microsoft's Hyper-V server virtualisation technology, which was formally launched today, along with a companion management tool, Microsoft System Centre Virtual Machine Manager 2008. 

"VMM is Microsoft's tool to manage a virtual infrastructure, it's their equivalent of the VMware tool VirtualCentre, but it is also a new point of failure," said Andrew Barnes, Neverfail's senior VP for corporate development. 

"Virtualised infrastructures bring their own management challenges. In this case, the difficulty is if you put your VM management tool onto a virtual platform, and that platform dies, you lose so much functionality."

Barnes said that, while it might seem counter-intuitive in a software-based virtualised infrastructure to duplicate a virtual server and keep the replica live as a hot spare, it remains necessary for critical services such as VMM. 

He warned though that replicating the entire VM is not enough to provide business continuity unless the replication tool can monitor the state of the application, not merely the state of the server. 

"You could use clustering to protect VMM, but that's more complex and requires enterprise software licences. Instead, Neverfail replicates at application level from one machine to another, whether virtual or physical," he said.

He added, "I also see big opportunities, in particular with Hyper-V, to use VMs as DR backups for physical servers, simply because as part of the Windows infrastructure it will already be out in the market - especially the mid-market."

Barnes admitted however that, while Neverfail's Continuous Availability suite can monitor the key application and library services underlying VMM, such as SQL Server, it is still working on a plug-in to monitor and manage VMM itself. 

"It is our intention to develop Neverfail for VMM, with delivery later this year," he said. 

Also promising support for Hyper-V was Acronis, which said that an update to its True Image software will enable the tool to create backup copies of Hyper-V virtual machines. 

The company claimed that True Image will be able to migrate images too, for example from physical to virtual, or from VMware to Hyper-V. It gave no date for the update's availability, though.