Although Microsoft has made decent progress in the virtualization race, there's no doubt that the leader in enterprise virtualization is VMware. VMware
has been in the virtualization business since the company released VMware Workstation 1.0 way back in 1999. In addition, VMware was the first to bring
bare-metal hypervisor-based virtualization to the enterprise, with the release of VMware ESX Server in 2001. VMware has a sizable lead in the
virtualization market; current market estimates show that the company holds about 75 percent of the enterprise virtualization market. In June 2011,
VMware released vSphere 5 -- even further raising the bar for enterprise virtualization. In addition, vSphere 5 continues to provide the foundation for
leveraging virtualization to build the private cloud (see the sidebar "vSphere and the Cloud").
ESXi Becomes the Hypervisor Standard
The core of vSphere has traditionally been VMware's ESX Server hypervisor. Eventually, VMware introduced the smaller-footprint ESXi hypervisor, which
the company provided as a free product. The ESXi hypervisor essentially had the same virtualization capabilities as the larger ESX Server, but it
jettisoned the service console -- replacing it with a limited character-based UI and remote management through the VMware vSphere Client. The
lighter-weight ESXi hypervisor also removes ESX Server's built-in web server, which means you now have to manually download the vSphere Client.
In vSphere 5, ESXi became the preferred hypervisor in part because of its smaller size but also because it has a reduced attack
vector, making it more secure. In addition, the new ESXi for vSphere 5 features a built-in firewall that lets you limit traffic by IP address and
subnet. vSphere 5 continues to support the older ESX Server hypervisor. The free version of the ESXi hypervisor is now called the VMware Hypervisor.
(For more information about VMware's migration from ESX to ESXi, see the VMware ESXi and ESX Info Center page.)
Streamlined vSphere Editions
VMware streamlined the editions of vSphere 5 by eliminating the Advanced edition. For vSphere 5, VMware provides the Standard, Enterprise, and
Enterprise Plus editions. The migration path from vSphere 4.1 Advanced is to vSphere 5 Enterprise. Table 1 summarizes vSphere 5's editions and their
main features.
All vSphere 5 editions use the ESXi hypervisor, and they all support vMotion, which provides the capability to move running virtual machines (VMs)
between ESX and ESXi servers with no end-user downtime. Processor and vRAM entitlement are related to changes in the vSphere licensing scheme. (For
more information about processor and vRAM entitlement, see the Licensing Changes section later in this article.)
vSphere Standard is the starting point for most medium-sized business. This edition includes support for VMs with up to eight virtual CPUs, as well as
support for VMware high-availability clusters and disaster recovery.
The Enterprise edition is geared for larger businesses. It adds support for hot-add RAM and CPU to running VMs, as well as support for Storage vMotion
and the Distributed Resource Scheduler (DRS). Storage vMotion lets a VM's files be moved to different storage locations with no downtime, whereas DRS
provides dynamic load balancing and power management for multiple ESX and ESXi hosts.
The Enterprise Plus edition is the top of the vSphere product line. It provides all the features in the Enterprise edition, plus it adds the
Distributed Switch capabilities, Host Profiles, and the new Policy Driven Storage support.
For centralized management, most organizations will also want to deploy VMware vCenter Server. vCenter Server is required to enable many of vSphere's
advanced capabilities. It lets you provision, monitor, and manage VMs. Two editions of vCenter Server are available for purchase: vCenter Server
Foundation and vCenter Server Standard. The vCenter Server Foundation edition lists for $1,495 and includes support for up to three vSphere hosts. The
vCenter Server Standard edition lists for $4,995 and isn't limited as to the number of hosts it can manage. This edition also adds process automation
through the VMware vCenter Orchestrator and multi-server insight with its vCenter Server Linked Mode.
Support for Huge VMs
One of the most important changes in vSphere 5 is its enhanced support for highly scalable VMs. VMware has always been the leader in VM scalability,
and with vSphere 5 the company extends its lead.
vSphere 5 VMs can have up to 1TB of virtual RAM, which is four times the virtual RAM supported by any previous release. The Enterprise Plus edition
also supports guest VMs with up to 32 virtual CPUs. Thirty-two CPUs and 1TB of RAM is enough capacity to run all but the most demanding workloads.
vSphere Storage Appliance
One of the things that has slowed vSphere's adoption in small-to-midsized businesses (SMBs) is that you need to have a SAN to take advantage of
vSphere's high-availability features, such as vMotion. Many SMBs use DAS and can't afford a SAN. vSphere 5 introduces the new vSphere Storage Appliance
(VSA) feature, which enables the creation of shared storage using DAS from two or three local ESX servers. Although its name implies that it's a
hardware device, the VSA is actually a software feature.
VSA works by dividing the non-boot storage space of a vSphere server in half and making each server node a primary for one volume and a replica for a
second volume. The storage is replicated and half of the storage is assigned to the replica. If a node fails, an election occurs between the remaining
nodes and the cluster directs the failover of the data store to the secondary replica.
Policy Driven Storage
vSphere 5 Enterprise Plus offers support for Policy Driven Storage. Policy Driven Storage lets the administrator create policies that determine where
VMs should be located and moved using Storage vMotion. Storage policies associate VMs, data stores, and SAN devices with storage profiles. They're
designed to ensure that VMs always run on the appropriate storage location to meet service level agreements (SLAs) for performance and to accommodate
the VM's space requirements. A storage profile identifies the storage characteristics that a particular VM should have.