VMware vSphere For Dummies
VMware vSphere 4.1 is the gold standard in virtualization, but it's also a large and complex solution for networking and cloud computing. Keep in mind the benefits of VMware vSphere when planning your virtualized environment.
How to Benefit from VMware vSphere 4.1 Features
If you're trying to decide if VMware vSphere 4.1 is right for your organization from a technological standpoint, consider these unique, high-value vSphere features before making your decision:
Memory overcommit: VMware vSphere 4 optimally allocates memory to virtual machines and leverages three different techniques to ensure that memory is available when needed. This capability recovers unused or wasted memory from virtual machines and allocates it to virtual machines with higher priority as required.
VMware vMotion live migration: VMware was the first to introduce live migration, which allows you to move running virtual machines from one ESX host to another without interruption. VMware also offers Storage vMotion, enabling migration of running virtual machines' disks from one vSphere datastore to another, without interruption to the virtual machine.
VMware High Availability (HA): vSphere offers High Availability capability that revives virtual machines from a failed ESX host by restarting them on another ESX host in a cluster.
Simple deployment of virtual machines (VM): VMware vCenter Server makes it easy for you to clone and customize virtual machines, giving each clone its own unique identity. This feature allows rapid deployment of virtual machines without building each one from scratch.
How to Save Time Installing vSphere 4.1
Installing VMware vSphere 4.1 is a complex process; you'll want to do what you can to make the installation go more smoothly. To make your life a bit easier, while preparing to install vSphere, use this handy checklist to save time and effort:
Shared storage: vSphere requires shared storage for functionality such as vMotion and HA. Make sure that each ESX host being deployed in a cluster has access to all the datastores assigned to the ESX cluster.
Networking: Connecting vSphere to your network is a lot like connecting an additional network switch. Confirm that the appropriate VLANs are associated with each ESX host's network connections and that VLAN tagging has been enabled accordingly.
Hardware compatibility: Check VMware's Hardware Compatibility List on its Web site prior to beginning installation. vSphere is pickier about its underlying hardware than traditional operating systems like Windows and Linux.
vSphere licensing: Although vSphere will run for a month or two using the built-in evaluation licenses, it's important to have your permanent licenses handy. Get those licenses installed before you forget and end up with virtual machines that refuse to start.
How to Know When Virtualization Is Improbable
Virtualization is an exciting technology, especially once you've realized the far-reaching potential and benefits of its deployment. Like the microwave oven, the Internet, or any other disruptive technology, people tend to get wrapped up in the complexities, feeling out the boundaries as they go. In some cases, though, virtualization isn't a viable option:
Hardware-based multimedia applications: Installing a multimedia interface card into a vSphere server does not allow you to map the card's capabilities to a virtual machine.
Telephony applications: Internet-based voice communications have seen mainstream adoption over the past few years, but the days of telco-based phone services are long from extinct. Several vendors still offer telco adapter cards for use in call centers, voicemail systems, and other interactive voice-driven applications. These card-based telco adapters don't map to virtual machines and shouldn't be installed in servers running vSphere.
Other virtualization products: Installing another hypervisor in a virtual machine usually doesn't work, and when it does work, the performance is poor at best.
Unsupported on virtualized platforms: Believe it or not, some software vendors out there still will not support their product if it's running in a virtual machine. That doesn't mean it won't work in a VM; the software will just deny you support for an issue if it's running in a VM when the problem occurs.
Licensing: Some software has licensing restrictions specific to virtualization, such as running a desktop OS licensed for use on a physical desktop computer.
When is unsupported really unsupported? Many times, even if virtualization isn't supported, you can get specific case-by-case support from vendors if you work closely with them. Before you rule out an application, try to contact your vendor. Depending on how large a customer your organization is, you may be surprised!