Last week during a customer presentation that I delivered, one of the attendees asked a surprising question:
What’s the difference between ESXi and vSphere?
While that’s an easy one for most VCritical readers to answer, there are newcomers that may benefit from a simple overview. If you’re here seeking vSphere understanding, welcome!
VMware vSphere Demystified
VMware vSphere is the industry-leading virtualization platform that consists of two primary products: VMware ESXi and vCenter Server. ESXi is the hypervisor and installs on bare metal hardware. vCenter Server provides centralized management and allows administrators to configure and monitor ESXi hosts, provision virtual machines, storage, networking, and much more. The vSphere Client is a Windows application that acts as a single pane of glass to manage either a standalone ESXi host directly or an entire datacenter though vCenter.
VMware ESX vs. ESXi
VMware ESX was introduced a decade ago and will be discontinued with the upcoming major release. Carrying the torch forward will be ultra-slim VMware ESXi, which has already seen several years of successful production deployments. Both products are bare-metal hypervisors — they install directly onto a server instead of a traditional general purpose operating system — and have the same capabilities, accommodating any licensed feature from Essentials to Enterprise Plus: vMotion, DRS, HA, FT, and more.
The primary difference is that with ESXi the Red Hat Linux service console is gone, leaving just the hypervisor and critical supporting features. By eliminating tons of unnecessary Linux components, ESXi footprint is measured in mere megabytes — not gigabytes like competitors.
Microsoft Hyper-V Server vs. VMware ESXi
I always get a kick out of well-meaning folks that try to claim that ESXi should not be compared to Hyper-V on Windows Server 2008 R2 SP1, insisting that it’s much closer to compare with Microsoft Hyper-V Server. Hyper-V Server, for those less familiar, is a free product that is essentially Windows Server 2008 Core with the Hyper-V role and a snazzy text-based menu that allows you to do a few key things — like run Windows Update.
Make no mistake about it, weighing in at several gigabytes and requiring care and feeding on Patch Tuesdays, Hyper-V Server is anything but a thin, purpose-built hypervisor. It’s Windows — just not the “Windows you know.” As Aidan Finn, Microsoft MVP and Hyper-V expert says, “…I would almost never install Server Core…”
Another vSphere Advantage over Microsoft Virtualization
Readers of VCritical have learned many of the technical advantages that ESX/i has over Hyper-V, but there is another advantage that vSphere holds over Microsoft when it comes to virtual infrastructure: By releasing both the hypervisor and the advanced management in lockstep, VMware vSphere is a platform that is greater than the sum of its parts.
You might be wondering, how a virtualization platform could introduce new, advanced capabilities if the hypervisor and management products are on different release cycles. No need to wonder, just witness Microsoft virtualization and see firsthand. Don’t take my word for it — look at how a real Hyper-V customer sees things:
It’s unbelievable that Microsoft would roll out new features to the virtualization product that are not supported in their virtualization management product… The Hyper-V and SCVMM teams don’t march in lockstep, and what updates they do release are too far apart.
Clearly Hyper-V customers have not been pleased with the manageability delays, but that’s not all…
The Bad News Flows in Two Directions
Later this year Microsoft will release System Center Virtual Machine Manager 2012, but the next version of Windows Server and Hyper-V is still merely the subject of speculation. This leapfrog release cadence creates a situation where VMM 2012 must attempt to overcome limitations with the platform by painting over them, in lieu of elegant solutions integrated with lower layers of infrastructure.
Consider this example: Instead of introducing a new streamlined hypervisor clustering capability, VMM 2012 attempts to orchestrate the 29 steps currently required to install, configure, and validate a failover cluster for use with virtual machines. Maybe some administrators will find it an improvement over the existing manual effort, but is it better than the simple drag-and-drop design found in vSphere?
Synchronized vs. Staggered
VMware vSphere is the leading virtualization platform for many reasons. It’s hard to understand how asynchronous hypervisor and management releases would be acceptable, let alone desirable. Just another compromise encountered when building a hypervisor on top of a general purpose operating system.