Understanding VMware vSphere, ESXi, and Release Cycles

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.

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10 Responses to Understanding VMware vSphere, ESXi, and Release Cycles

  1. Stu Fox says:

    Is an integrated platform like when you released vSphere 4 U2 and it broke PCoIP for View? Is that the sort of thing you mean?

  2. James Richard says:

    Let us see some examples from VMW own product stack of products that are inconsistent-
    1. vCloud Director is extremely difficult to install and works only with RHEL and Oracle databases (no SQL support) in its present version.
    2. It’s automation software – vCenter Orchestrator is not integrated with vCloud Director. Can you believe a private cloud without automation? Certainly VMW thinks it’s possible.
    3. It is missing a robust policy engine or any kind of SLA framework
    4. I have talked to many admins and they say getting vCloud director working is extremely difficult- someone spent weeks and still couldn’t get all pieces working..

    List goes on..the point is not whether a product has all the features at a given time. the point is that Hyper-V is gaining market share 3 times faster than ESX/ESXi according to latest IDC numbers and since 80% of VMW revenues comes from vSphere, they want to protect that turf from their competitors, mostly Microsoft.
    So this kind of article that basically doesnt have a valid point..

  3. Danny says:

    Gee, James and Stu, why don’t you compare apples to apples? The obvious point of the article was to only show how the hypervisor and management server releases differ between the two vendors. View is neither of those and I’m sure MS has never released a patch or upgrade that broke another products functionality; otherwise we would have to test all of those patches before installing on production.

    At least Stu is transparent in his relationship to MS. Too bad James wasn’t as honest.

    Bringing Cloud into the discussion is, again, a desperate attempt to misdirect. Market share figures and competitive practices??? Wow, what next? Comparison of CEO lifestyles???

    • Stu Fox says:

      Danny, maybe it’s because Eric is full it and he knows it? Like his cherry picked “customer quote” (to be fair, I wouldn’t necessarily call a blog comment a “customer quote”, like I wouldn’t call my comment on Eric’s blog “an official Microsoft position”) from a blog article in October, a full 5 months before dynamic memory shipped.

      When Hyper-V releases new features, VMM supports those new features in a reasonably short timeframe. Windows 2008 R2 SP1 was released in February, VMM SP1 was released the next month in March. Sure, it’s not a synchronised release, but it’s not an un-coordinated release either. On the flip side, doing it this way means that VMM can release on a faster cycle than Hyper-V can, which means we can add additional management capability quicker – for instance the Server App-V technology that is coming in VMM2012 (to choose just one example). If it were VMware we’d be waiting until they had a hypervisor release to do.

  4. Larry says:

    This is funny stuff. It good reading on one screen, while on the other SCVMM 2008 R2 converts VMware VM’s to Hyper V.

  5. Stephen says:

    I’d argue that both Vmware and MS will be blindsided by Xen in the hypervisor/managment space.

    Definitly an interesting few years coming up!

  6. Salty says:

    I am still confused on the point of can you do anything with the free ESXi hyperviser offered by VMWare, or is it strictly useful when purchased with vSphere?

    Just so I don’t get a bunch of answers asking how/why I would want to do this in a data-center environment… I don’t!

    From a small (home) lab perspective, can I install and use ESXi to host and interact with various guest OS without purchasing vSphere?

    • Eric Gray says:

      Yes, stand-alone single host home lab is an ideal use case for free ESXi. You would install the free vSphere Client on Windows and just point directly to the ESXi host for VM management. Clustering, vMotion, HA, and other more advanced features are enabled by vCenter Server.


      • Salty says:

        Thanks! That is what the VMware site seemed to indicate, but I didn’t want to wast time then find out it does not work.

  7. Mike Birmingham says:

    Thanks for clarifying product names for me – I wasn’t sure what to download prior to reading this. The change in product names/versions is getting as confusing as Citrix!

    I also enjoyed the blog fight at the end – very entertaining thanks guys! As an agnostic contractor, I have to say please never get your products 100% bug free…you’ll do me out of work!

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