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ESXi vs. ESX: A comparison of features

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VMware made the decision to make VMware ESXi, our next generation hypervisor, freely available to proliferate the VMware platform and allow administrators to prove its value at no cost. However, the fact that the older platform, VMware ESX, is not also available for free has lead some people to believe that ESXi may be inferior or not as feature-rich as ESX. This is certainly not the case. In fact, the opposite is true. ESXi has a superior architecture and we encourage customers to deploy ESXi as part of any new vSphere deployment. Our future posts will compare ESX 4 and ESXi 4 in detail on topics like hardware compatibility list, performance, and management to demonstrate that ESXi is either on par with or superior than ESX. But for now, here are some key points you should know about ESXi vs. ESX:

  1. The functionality and performance of VMware ESX and ESXi are the same; the difference between the two hypervisors resides in their packaging architecture and operational management. VMware ESXi is the latest hypervisor architecture from VMware. It has an ultra thin footprint with no reliance on a general-purpose OS, setting a new bar for security and reliability (learn more).
  2. In the future, ESXi’s superior architecture will be the exclusive focus of VMware's development efforts.
  3. New and existing customers are highly encouraged to deploy ESXi. Many Fortune 100 companies have already standardized on the ESXi platform.

Although one instance of free VMware ESXi can be managed with the vSphere Client, the free version has two important limitations:

  1. vCenter cannot manage free ESXi without a vSphere license as its APIs only grant read-only access.
  2. Automated scripts cannot change hypervisor settings. 

However, once ESXi is licensed for any vSphere SKU, its APIs become both read- and write-accessible, unlocking the full functionality of vCLI, vMA, PERL Took Kit, Powershell Tool Kit, or other VMware management interfaces.The table below, available here, explains how different license levels unlock ESXi (and ESX) functionality. Please note that vSphere Essentials, an all inclusive package that can be deployed on up to three servers, is priced at under $1000. 

The ESX Team


30 thoughts on “ESXi vs. ESX: A comparison of features

  1. VMDoug

    Can you clarify the official name of the version of ESXi that is free?
    Is it
    ESXi Free
    Free ESXi
    Unlicensed ESXi
    ESXi Single Server
    or some other combination that is not currently known. I’ve heard all of the above except “ESXi Singer Server” from VMware employees.
    Doug Hazelman
    Veeam Software

  2. Amir Sharif

    The official name of the free product is VMware ESXi 4.0. VMware ESXi 4.0 can be licensed to vSphere 4. vSphere 4 allows for multi-host management and provides full access to the APIs.

  3. Amir Sharif

    Let’s focus on acquiring ESXi instead of buying it. This makes the conversation easier for reasons that should become evident.
    Bit-wise, acquiring ESXi is no different than acquiring vSphere. The downloads are the same; vSphere functionality (SKU dependent) is unlocked by various licenses that you can purchase.
    ESXi/vSphere acquisition is independent of vCenter. These are different products.
    ESXi can be acquired at no charge on vmware.com (no buying). ESXi can be acquired for a (generally nominal) fee from a server vendor.
    vSphere can be purchased from VMware or many VMware partners.
    Likewise, vCenter can be purchased from VMware or many VMware partners.

  4. Jon

    So, let me get this straight…
    You can download and install the ESXi single server hyper-visor for free.
    But to manage it, you need vSphere or vCenter.
    vSphere is available for free as a 60 day trial.
    Personally, I feel like you’re advertising a free car, but then telling people its the keys and title that have a cost.

  5. Amir Sharif

    Not exactly.
    You can manage a single ESXi instance through vSphere Client – which ships with ESXi. vSphere client gives you full management capabilities.
    You cannot, however, use APIs to manage the single host, and you cannot leverage the multi-host capabilities that come with vSphere and vCenter, like vMotion, DRS, and HA.

  6. VMCreator

    No No No !. The bottom line gentleman is that if VMware do not provide a free ESXi AND a free restricted vCenter combined with public access to the VMworld presentations 3 months after its closure, then there will be a mass migration of good VMware experts over to Hyper-V,
    The reason is, that there are thousands of “One man band” VMware supporters i.e freelance consultants that cannot afford the cost to purchase full blown versions of VMware and its product set.
    Does this ring a bell?, YES pretty much the same as all the Novell CNE’s that were left on the ropes and not supported by Novell.
    You have to remember that we are the people that get into the business, education and public sector shops because we are cheaper to employ and we are like psuedo “sales reps” for VMware – thousands of us!promoting your products.
    Just look at all the blogs and help pages on single whiteboxes for home use!.
    Please do not go down the Novell route or you will not compete with the Microsoft giant. – ACT NOW before it is too late!.
    VMware VCP [Freelance Guy] – UK

  7. Adam

    I have never used ESXi so before I even download the files to try it, I just wanted to get clarification on what was said earlier post:
    “You can manage a single ESXi instance through vSphere Client – which ships with ESXi. vSphere client gives you full management capabilities.”
    If I install ESXi on a single physical server, and install vSphere client on a separate single physical client, I can manage all virtual machines on the ESXi host?
    For a moment it looks like you are saying that the vSphere client may only manage the first virtual machine created and if you want to manage more you need to license vSphere (the word “instance” is creating the confusion).

  8. Amir Sharif

    Excellent question VMCreator.
    Yes, vSphere Client (installed on a client machine) allows you to manage *all* VMs on the ESXi host machine. You are *not* limited to managing only a single VM on the ESXi host.
    What you cannot do is manage multiple ESXi hosts simultaneously (you are required to log into each host separately).
    To install vSphere Client, download ESXi and install it. Once you have set up the network, use a browser on the client machine to point to the IP address of the ESXi host. You will be able to download vSphere client directly from the host for installation on the client machine.
    I would appreciate your posting your comments here after you try this out.

  9. Amir Sharif

    ESXi does not limit the number of CPUs per server; it will run as well on a single- or quad-CPU (socket) system.
    There is a limit to the number of cores per CPU. Please refer to the chart above for details.

  10. Christophe Grayet

    the licence I’ve received is for one physical CPU. And yes, the server has two quadcores and ESXi is seeing only one. You said that ESXi does not limit the number of socket… So, limited or not limited?

  11. Nenad Cuturic

    I agree with Christophe – looks like limitation for “free” ESXi is to 1 (single) physical CPU.
    Though I have only one plugged in but had plans to plug in the second. Now very seriously considering to run hyperV (I’ll run win 2008 R2 on it anyway).
    Even VMware staff doesn’t know license agreement details and goes out with misinformation.

  12. Thomas Jensen

    How exactly are you inferring that the ESXi license is restricted to one processor? The license keys we issue for ESXi 4.0 are not restricted to single-socket servers, so either there’s a bug somewhere or it is a misunderstanding. Can you please elaborate?

  13. ITguy

    I can confirm that ESXi will use more than 1 socket. I’m running the free version of ESXi 4.0 with 2 x quad-core Xeons. All 8 logical CPUs are available to ESXi, and my free vSphere client is able to manage all VMs on the server.
    I will say that the vSphere client seems a bit bloated and sluggish compared to Citrix XenCenter. It was also disappointing to learn that VM cloning with templates, which I expected as a basic feature, is disabled on ESXi without a fully licensed vCenter. I’m not sure what that maps to in the feature chart, maybe “Host Profiles”?

  14. questionman

    Q: ESXi only works on specific hardware. So it is not White Box capable. This limits it’s use and deployability.

  15. Shadow

    Downloaded, installed ESXi 4 on a BL495… pretty smoothly. For my company needs it’s just perfect. I won’t pay the extra for “managing multiple hosts” right now, because right now we only have one host that can keep the pace with multiple VMs. There are some issues, like I couldn’t export a VM installed with SuSE Professional 8.2 (I know, I know, old stuff, but hey, old stuff still running for years now) – how about that ?! It finishes with an error saying something about a timeout (the export thing is very slow, hundreds of hours, for some unknown reasons). On the host, tab “Configuration” -> Sensor -> Other it says “System Board 2 ProcHot – Limit exceeded” and marked with “Warning”. I checked the server from the OA and everything is OK. But overall, pretty nice product, escpecially taking in consideration it costs, well, nothing…

  16. Johnny Thrash

    I’ve installed the VMWare ESXi 4 software and the vSphere Client link is broken. Can you please just make the client available on the website?

  17. Thomas

    One major problem with ESXi vs ESX. VMware does NOT support boot-from-SAN for ESXi, whereas it does for ESX. This forces customers to use some type of internal storage in servers, be it a USB key, SDHC card, or disk drives. In a blade environment where we want to re-assign physical servers to different roles, requiring ESXi on local storage is a major problem. But the security folks don’t want ESX due to all the issues associated with the Linux-like console.
    VMware PLEASE officially support boot from FC SAN for ESXi.

  18. Alex

    given the fact that ESXi has only a small footprint why would you need to boot it from SAN (may it be FC, iSCSI, FCoE etc)?
    it’s true that you are dependent on having internal storage for the servers on which you install ESXi (USB, CF, SDHC, HDD etc) but that type of storage is available in any server.

  19. YAN

    I am keep getting license isse that my license is going to expire in xx days.
    I download ESXi4 and installed it on a single PC only and try to registered on line, but keep getting that this license is alread registered.
    How can I correct the license issue.
    I do not want to reinstall ESXi4 again?

  20. Joe

    My company is looking at purchasing either Essentials or Essentials Plus.
    We have currently deployed one ESXi 4 host on a Dell PowerEdge server and ready to add a second ESXi host on a second Dell PowerEdge server.
    I am running VMWare Workstation on my high-end Xeon desktop computer and have installed vCenter in a VM on my workstation. vSphere Client is installed on my desktop host OS, Vista, and connects to vCenter in the VM to manage the ESXi 4 hosts. I will likely be moving the vCenter VM to a VMware Server 2.0 running on a separate system since this is a free product. All VMware products are currently running in eval mode, other than the free VMWare Server 2.0. We will eventually have 3 Dell PowerEdge servers running ESXi 4. What we need to do is evaluate the addtional features in Essentials Plus while everything is in eval mode to determine if Essentials Plus will do what we need. We want to do a proper evaluation with all 3 ESXi hosts online running multiple VMs. My questions are as follows:
    1. I already have a key to run my first ESXi 4 host. Can I use that same key for the second and eventually third ESXi 4 host? If not, how do I obtain 2 more keys to run ESXi 4 free while I evaluate vCenter with vSphere client?
    2. How do I trial the features of Essentials Plus, specifically the HA and Data Recovery, while in Eval Mode with 3 running ESXi 4 hosts?
    We will be purchasing either Essentials or Essentials Plus depending on our eval before the eval period ends.
    Perhaps someone from VMware can answer me via this forum or contact me.
    Please advise.
    Thank you very much.

  21. Interested

    Just wondering if there is support for ESXi or is it only for ESX?
    What is the cost for the support contracts for ESXi if there are any?

  22. Dimitris Zahos

    It is really being offered a free car but without wheels. With the free ESXi update 4, there is no way to have an automated backup of the vms! All features are locked and a new license is required. Deeply dissapointed and thinking seriusly to migrate to Microsoft’s Hyper-V.

  23. Mike

    I’m a bit confused here. We are currently running 6 ESX 3.5 standard servers. These servers host various guest servers used primarly for development purposes. We currently don’t have vCenter but are considering purchasing it. We are looking to move to vSphere 4, should we be going ESX or ESXi or does it matter since we are licensed users.

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