PAGE 2
Introduction
Server virtualization is gaining tremendous popularity among of modern datacenters. As a technology solution, it offers the promise of reducing capital and operating costs by consolidating physical servers, reducing down time, and speeding deployments. Although server virtualization can reduce costs on the server side, it brings with it a new set of I/O challenges. These new I/O challenges threaten to substantially reduce the savings of server virtualization.
The I/O challenges from server virtualization stem from the inherent consolidation and flexibility of virtualization. When multiple physical servers are consolidated into a single machine and then virtualized, the I/O resources from all of those servers must combine onto the single server. This can quickly explode the resource requirement of
the physical machines, both in number of connections and the speed of those
connections. Additionally, the reduced down time and faster deployments made possible by virtual server mobility come at the price of requiring SAN storage and unilateral resource availability.
To successfully deploy virtual server solutions, datacenters must address four key shortcomings of current server I/O:
n Virtual servers increase the number of network connections required on a single
server, resulting in increased CapEx costs for switches, NICs and cables and cable installation/management
n As virtual servers are added to physical servers, the utilization of server I/O increases,
requiring higher peak bandwidth usage than the physical servers would see alone
n In order to effectively implement virtual server migration, SAN storage is required per
host server
n When virtual servers are migrated from one physical host to another, all I/O resources
PAGE 3
So What’s the Problem?
Server virtualization is growing rapidly in popularity. Gartner estimates that 50% of the workloads will be running on virtual machines by the end of 2012.The value proposition is well understood. When used as a consolidation tool, there are tremendous savings in both CapEx and OpEx spending. The consolidation of servers may result in server side savings, but will put pressure on the cost of I/O for those servers because each virtual server consumes I/O resources, even when deployed with other virtual servers on a single machine.
For example, each virtual server likely runs the same applications it did or would have if deployed on a single physical machine. Those applications require accesses to specific networks and have bandwidth requirements. The datacenter network provides the same resources for a virtual server as a physical server. Thus, hundreds of virtual servers may now reside in the same rack, when previously, 30 or 40 physical servers may have resided inside of a single rack. This can double or triple the I/O resource requirements.
Additionally, each application has potential security or access rights and even when virtualized, those access rights must be maintained. As such, a single physical server must have all of the access rights to all of the virtual servers residing on that physical server. In cases where unique networks or storage are required for applications, this can multiply the number of physical network and storage ports by a factor of five.
Finally, virtual servers require shared storage connectivity for best practices, specifically for vMotion support. Shared storage is typically on a storage area network (SAN), but can also be implemented using iSCSI and NAS shared storage. In non-virtualized physical servers, Fibre Channel storage is at a low adoption rate (typically below 20%), however, if implementing best practices for virtual servers, that penetration can jump to nearly 100%. This dramatically increases the cost of I/O for the physical hosts, as those host servers would normally not have Fibre Channel connections.
In total, the I/O complexity for a virtual server solution grows substantially compared to a non-virtualized server.
“Most organizations will
be well-served by focusing
attention on the challenges
within the server rack.
The increasing density
of bandwidth has forced
many organizations to
significantly increase the
number of adaptors, and
solving the I/O challenges
significantly simplifies the
rest of the architecture.”
Gartner GroupPAGE 4
Taking Virtualization to the next level with I/O Virtualization
I/O Virtualization (IOV) is the next logical step in server virtualization to simplify the complex I/O common to virtualized solutions. In its essence, I/O virtualization creates consolidated resource pools of I/O that are available to any server in the rack. Instead of physical I/O housed inside the server, IOV separates the I/O from the server by connecting the server to the IOV resource pool through a simple, single PCI-Express (PCIe) cable. In the optimum solution, the IOV resource pool allows for sharing of a single I/O resource across multiple servers within the rack. This combination of pooling and sharing reduces the cost and complexity of I/O while giving the greatest flexibility of assigning and re-assigning resources to servers as needed. An effective I/O virtualization solution needs to have three key elements for success:
• First, it must be low cost. An IOV solution that does not reduce the CapEx problem created by virtual servers fails the first order in the value proposition.
• Second, it must have a broad range of I/O resources available. Since virtual servers cross a wide range of applications, all require different I/O solutions.
• Third, it must be simple and non-disruptive. Many more virtual servers will be added to a given server rack, placing a larger burden on the entire rack solution to be easier to use than a physical server environment.
NextIO has developed a simple, low cost I/O virtualization architecture based on PCI Express. NextIO utilizes PCI Express because it ships with every server for free, covers all I/O devices in use by servers today, and is based on industry standard hardware and software. Using NextIO’s IOV architecture, datacenters can pool I/O resources from industry standard adapters and share them across multiple physical machines. These shared resources use standard software on the server and can be upgraded on the fly.
PAGE 5
The Value of IOV in Virtual Server Infrastructures
I/O virtualization is a clearly the next logical step for efficient connectivity of virtual servers and hosts inside of a rack. An effective implementation, like NextIO’s PCIe IOV architecture, simultaneously lowers the hardware cost of implementing virtual servers and increases the flexibility of the solution.
IOV uses a single standard PCIe cable for many resource connections. This addresses the virtual server requirements of connecting to multiple networks in a cost effective way. As more virtual servers are added to a single host, that host can access more IOV resources without new hardware or cabling. Cost reductions of up to 50 - 80% are common with effective IOV architectures.
Further, IOV’s pooling of resources allows for sharing of resources and access by all servers in the rack. This solves the virtual server requirements for cost effective SAN storage access and availability of resources to virtual server hosts. As hosts are deployed in the rack, they can readily access any or all of the IOV pooled resources. As I/O demands increase and more bandwidth is required, I/O can be added to the pool without physically touching any server. NextIO’s I/O virtualization solutions simplify the complexity of I/O within any virtual server environment. CapEx savings of up to 50 - 80% for server I/O are easily achieved by
reducing the number of adapters and switch ports required in the rack. Datacenters also see tremendous OpEx benefits by enabling a flexible resource pool that can follow virtual servers as they migrate from machine to machine.
For more information visit: www.nextio.com
