With all the changes virtualization brings, it’s easy to forget what makes the whole thing tick: hardware. Virtualization hardware affects performance, efficiency, resource allocation and virtual machine (VM) density.
But choosing the right hardware for virtualization can be difficult. You need to consider costs, space, compatibility and resource requirements -- not to mention vendor options. This guide breaks down your virtualization hardware choices, specific VMware hardware considerations and ways to get the most out of your virtual server hardware.
TABLE OF CONTENTS
Choosing virtual server hardware is difficult. You can use traditional servers or a blade chassis and traditional or virtual I/O cabling. There are also numerous ways to address network connectivity. Finally, you must decide whether to manage your virtualization hardware with tools from a hardware vendor or a third party. The following video and links will help you choose hardware for virtualization.
How to select hardware for virtualization
Virtualization hardware options: Vendors and servers
Cisco Systems, Xsigo Systems and Afore Solutions are a few of the major virtualization hardware vendors, and there are many more options. Blade servers simplify management and cabling, but make sure the blade chassis scales to your expected performance level. Traditional physical servers, on the other hand, often scale higher, allowing for greater amounts of CPU and RAM to run on a greater number of VMs. In addition, virtual I/O tools can simplify virtual server hardware cabling and reducing the cost of connections and switches.
Blades vs. rack servers for virtualization hardware
The blade vs. rack server debate focuses on pricing, features and management capabilities. Traditional rack servers typically have a lower entry cost than do blades, and they don’t require power supply modifications. But blades offer a centralized management console, which increases efficiency, and blade enclosures facilitate VM load balancing. Many of today’s blade servers also offer automation, as well as plenty of ports and Fibre Channel interfaces, which wasn’t common in earlier blades.
Choosing the best virtualization hardware and storage protocols
In the past, hardware for virtualization required admins to separate role-based network connections on physical media. For many, this approach is still a best practice. But it’s now possible to stack roles on adapters, including those on different virtual local area networks, because most server virtualization hardware has four built-in Gigabit Ethernet ports. Admins should also consider storage protocols in tandem with virtual server hardware, because port costs can affect hardware purchases and configuration.
Server management: Hardware vendor or third party?
One of the most important decisions regarding hardware for virtualization is choosing the right server management tools. The type of virtualization hardware you have, how you want to manage the servers and pricing all come into play. If you want reliability, buy management tools from your virtualization hardware vendor, because their offerings are likely optimized to work together. But if you have a mix of old and new hardware, it’s harder to manage virtual server hardware with vendor-supplied tools.
Once you’ve selected hardware for virtualization, you can use the virtual hardware to gather important data about your infrastructure. But incompatibility between virtual server hardware and software could lead to virtualization problems. And think twice about ditching old switches, servers and other hardware that seems to have lost its usefulness.
Putting old data center hardware to use
Virtualization decreases the amount of hardware (and its associated costs) in the data center. But as you consolidate servers and create VMs, switches and other hardware are often left behind. You can save old data center hardware to serve as backup. Many shops also place mission-critical VMs on newer virtualization hardware and run less important VMs on old hardware. Other departments in your organization could even put your leftover hardware to good use.
Using virtual hardware metrics to hit a performance home run
The server consolidation ratio, or VM-to-host ratio, is one of the most important virtual hardware metrics. This ratio depends on the physical host configuration and VM resource requirements. To boost VM density, you can add more physical machines or add resources to an existing server. Just remember, the more VMs you stuff onto your hardware, the greater number of VMs that will crash during a failure.
Hardware compatibility issues lead to virtualization problems
After an environment is virtualized, backup tools and other hardware-dependent software sometimes won’t work as expected because of the added abstraction layer. If your backup process relies on USB drives, for instance, it may have trouble connecting to the network. Know your virtual server hardware requirements before you begin virtualizing, and remember to test virtualization hardware compatibility.
Hardware for virtualization: A new approach for the private cloud
As cloud computing matures, hardware for virtualization will evolve. Instead of purchasing traditional servers and storage for virtual hardware, admins will buy units of processing and units of storage. That way, the focus is on resource demands, and you can buy units in measurable amounts from hardware vendors. This strategy also means you can plan better for VM needs and virtualization hardware will function at its optimal capacity.
IT chargeback based on virtual server hardware
One IT chargeback system for virtual data centers is to have departments pay for their own hardware. That means the department can add VMs without any hardware-related charges. But some organizations’ security policies prohibit certain VM deployments and provisioning, so the department might have to purchase additional hardware. And if the company requires fault tolerance, virtualization hardware can get pretty expensive.
In a VMware infrastructure, you can’t use just any old hardware. VMware-supported hardware must meet compatibility requirements and must be fault tolerant. Hardware for virtualization in VMware shops can be limiting, so make sure everything -- server makes and models, network adapters, storage adapters and storage devices -- meet the VMware hardware prerequisites.
VMware hardware requirements make Hyper-V more appealing
VMware’s Hardware Compatibility Guide lists the virtualization hardware compatible with VMware vSphere. VMware hardware requirements are so specific because device drivers must be included in vSphere for it to support certain hardware, and the drivers are adapted for the VMkernel. So if there isn’t a driver for a certain hardware device, it won’t work with vSphere. Some VMware-compatible hardware won’t work with future vSphere releases, but Microsoft Hyper-V, on the other hand, supports a wider range of virtualization hardware because it is part of the Windows operating system.
Selecting VMware hardware for ESX environments
The Hardware Compatibility Guide has three sections: systems (server make/models), storage devices (SAN/iSCSI/NFS) and I/O devices (network interface cards/storage controllers). Specific hardware is tied to each version of ESX and ESXi, but VMware offers CDs with custom drivers so you don’t have to wait to install the hardware you want. Also, some features will work only with certain VMware-supported hardware for virtualization.
Hardware choices for VMware home labs
There are many VMware hardware options for home labs, depending on costs, feature support and your vendor preferences. You can use brand-name, pre-built desktop PCs or servers, or you can build your own white-box PC. When it comes to server models, shop around for the best price and make sure vSphere supports the storage adapter and network interface cards (NICs). Check out dual in-line memory modules and dual-port NICs to beef up your lab’s virtualization hardware.
This was first published in May 2011