As a potential first step to meeting shared SAN requirements across virtual servers, Augie Gonzalez, director of product marketing at DataCore Software ( http://www.datacore.com/ ), suggests using portable storage virtualization software to make the disks inside the existing physical servers shareable. “The storage virtualization stack will run inside its own virtual machine (VM) or right on top of the hypervisor. From there, it first virtualizes formerly dedicated drives into shared iSCSI resources accessible from multiple VMs over a conventional LAN.”
...At the point where application workloads consume more than 75% of the physical server resources and the number of servers grows, DataCore’s Gonzalez advises moving the storage virtualization software into a pair of small dedicated servers that can handle the expanded capacity and I/O demands of the bigger environment. This, too, is straightforward, as the software licenses are fully portable from virtual to physical machines. Achieve further cost containment by relocating the original internal drives behind the storage virtualization nodes before any more storage is added.
...Many of the storage applications are dual mode, meaning they can reside in either a virtual machine or a dedicated physical host. DataCore’s Gonzalez believes this gives SMEs the best of both worlds. SMEs can start small, leveraging internal disks, and then as the production environment ramps up, they can move the storage to a dedicated system. Throughout that process, shared storage is available, but cost and complexity are kept to a minimum.
• Shared storage is critical for maximizing the benefits of server virtualization, and now it is also affordable for the small to midsized data center.
• Leveraging the server virtualization project itself either through the use of virtual machines or by repurposing legacy servers is a key element in driving out costs.
• Simplicity is as critical as reducing hard costs; SME personnel typically wear multiple hats, and integrating storage management into the virtual server management console reduces complexity significantly.