We examine five products that marry high availability and disaster recovery to your virtual server environment
The process of managing a protected copy of Windows remains the same. Any action taken on the primary copy is duplicated automatically on the second copy. It is possible to protect server instances on both XenServer systems: You can protect a primary instance or multiple instances on the first, which are duplicated on the second, and one (or more) instances on the second, which are duplicated on the first. Of course, care should be taken to ensure that if one physical server fails that the other won't be overloaded. After a failure is repaired, everRun automatically resynchronizes the two instances; there is no need for administrator intervention.
everRun VM is limited in scope, currently supporting virtualization of Windows Server 2003, and only on XenServer. However, what it does, it does very well, providing the highest level of fault tolerance and great ease of use. At $2,000 per physical XenServer, or $4,500 for a license for both XenServer and everRun VM, it is reasonably priced for a continuous high availability solution.
Scalent Systems Virtual Operating Environment
Scalent Systems' software is not storage virtualization software, nor network virtualization software, nor deployment software: It's an integrated platform that enables admins to quickly and easily deploy, move, repurpose, and clone server instances, automatically changing network settings, storage and LUN settings and more to reflect the needs of each system. By integrating control of your network switches, storage switches, storage hardware, and virtual environment into a single console, it provides flexibility and capabilities that are hard to imagine if you're used to a standard hardware-based environment.
Scalent V/OE (Virtual Operating Environment) uses the capabilities of VMware 3.5 to create instances that boot from SAN, then makes those instances completely portable. As such, you can move a server OS from a physical instance to a virtual instance, to a virtual instance on another VMware server, and even back to a physical instance, all without ever having to copy files or change any settings manually.
Suppose, for example, you have a Windows 2000 instance running in the test network. With the development finished, you might have a requirement to move it to the production network. In a typical hardware-based scenario, this would involve changing many settings internally on the server -- and possibly moving the server hardware, or at least changing the physical network connections to a different switch.
With Scalent, you would simply drag the icon from one group to the other. The system would then automatically change the VLAN settings on the appropriate switch, the network settings on the server instance, the LUN masking and other storage settings, the VMware partitioning, and virtual name of the HBA for the server instance, and the server would be in its new role. (You do need to change the HBA that the boot-from-SAN image is linked to.) No files actually have to be copied anywhere. Each server needs to have a lightweight agent installed, but it has minimal impact on the system.
Because storage replication features can be used to keep the boot-from-SAN images up to date in a backup datacenter, switchover time is very quick, limited to the time it takes the OS to boot from the new SAN image in the new location (typically faster than booting from a local disk).