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What’s the difference between free ESXi and licensed ESXi?

Updated 12.08.08The difference between free ESXi and licensed ESXi has been a very popular topic and one of my most read posts. Now with the release of ESX/ESXi 3.5 Update 3 there have been some feature changes in the free ESXi that I want to point out. I have also made a few corrections. I have left my original text for reference. Thanks go to Mike Dipetrillo for asisstance with these updates.

update 12.15.08 – the ESXi 3.5 Update 3 RCLI API was unintentionally opened. The remote administration abilities will be locked down again in the next release. Please see my updated post on this new information.

In case you’ve been “holed up” in the data center for the last month (I don’t doubt that a few admins have) and maybe haven’t heard yet, VMware now offers a free version of ESXi. Yes, VMware has made a version of it’s enterprise class, bare metal installable hypervisor available for download at no charge. There is no trial period or demo license required. There are no guest limitations on the host. So, there has to be a “gotcha”, right? Not really, but you do need to understand the differences between the free ESXi and VI ESXi (licensed) versions.

Although ESXi runs the same code and is on the same distribution schedule as ESX, VMware’s intended usage is a little different than what VMware administrators are used to, and therefore the ESXi product has some functional differences that need to be understood – especially for the free ESXi version. This post explores some of the major differences, and can hopefully help VI administrators make the correct decisions about what version of ESX to implement. I concentrate most on the differences between the free and licensed versions of ESXi as they are the most likely versions to confuse administrators used to VMware’s full ESX 3.5 enterprise solution.

ESXi is a stand alone appliance

Both in the way ESXi is installed and in the way it is updated or patched, ESXi is more like firmware than it is like a operating system. The installation routine does not require normal configuration decisions. For example, the install does not prompt for partition sizes. Once installed, ESXi does not provide root access to a shell like the Service Console available in ESX. In fact, ESXi is VMware’s hypervisor code only and no longer has any remnants of the Red Hat distribution. VMware designed the ESXi host to be managed individually with the VI Client. Finally, patches and upgrades will be full image replacements.

So, what would be some good uses of ESXi? In the VMware Communities Roundtable Podcast #11(linked at the end of this post) the following scenarios were suggested as appropriate:

    • Companies starting out with virtualization
    • IT departments with little Linux experience
    • Small office or department deployments
    • Remote site deployments
    • Creating simple test and development environments
    • Small consolidation scenarios
    • Quick DR site implementations to get most of the most important VMs up and running
    • enterprise companies that want stateless servers with small footprints that can be quickly deployed

Also, if ESXi is a stand alone host only, then why use ESXi instead of the also free VMware Server?

    • ESXi is a bare metal install and VMware Server requires a host operating system.
    • There is more resource overhead used by the host operating system when using VMware Server.
    • ESXi is an Enterprise class hypervisor that can run more guests
    • ESXi can be directly upgraded to VI3.5 Enterprise when ready

Remote Administration and Monitoring

Remember, the key difference between ESX 3.5 and ESXi is the presence of the Service Console OS. Without the Service Console the remote administration and monitoring possibilities have changed significantly.

free ESXi

  • Remote administration only possible with the VI Client
  • Although the Remote Command Line (RCLI) appliance is available, the free version’s RCLI access is read only
    • Can not change things – Can’t create new vSwitches or configure existing vSwitches for example, just read current config
    • getting a read and write RCLI is an upgrade to VI Foundation, VI Standard, or VI Enterprise.
  • Can NOT use SSH / WinSCP / mRemote – there is not a Service Console. ( it is possible to open a busybox console as explained here and here, but this function was intended for VMware Technical Support only. If you listen to the VMTN Podcast mentioned earlier it is very clear that VMware does not support this access by it’s customers and is also seriously considering removing this function completely.)
  • can NOT use SNMP monitoring

updated 12.08.08- As of ESXi Update 3 the RCLI is no longer read only. You can read and write changes thus making remote administration possible. It is also possible to use the normal ESXi API for administration, and several new gui based tools are beginning to surface with ESXi management ability.

Correction: Even with the free ESXi version CIM agents are provided and SNMP monitoring is possible

Updated 12.15.08 – The RCLI for the free version of ESXi 3.5 will be locked back down again in the next release

VI ESXi (in VI Foundation, VI Standard, or VI Enterprise)

  • Licensed versions of ESXi also lack Service Console and remote SSH ability. (see updated note above for same alternatives)
  • Can be managed by VirtualCenter Server as well as VI Client
  • RCLI is read and write
  • SNMP monitoring available wih built in CIM agents

Scripting of Installation and Configuration

The current scripting available in the full ESX 3.5 is possible because of the Service Console so we will concentrate on the other versions again.

  • Web Access does not exist for ESXi
  • Kickstart based automated installation is NOT available
  • Read only RCLI prevents scripting in free version but licensed VI ESXi can use new RCLI commands to provide scripting
    • VMware recommends current scripts be ported to new RCLI syntax
  • RCLI does have a built in command to export host configuration and import to other hosts

updated 12.08.08 – Mike Dipetrillo from VMware pointed out that you can PXE boot and even Kickstart ESXi . installs. See his post on this here:

As of Update 3 the RCLI is no longer read only so scripting not prevented anymore. see notes above

Correction: The RCLI command to export host configurations apparently is still a future feature. Look for it in upcoming versions.

Updated 12.15.08 – The RCLI for the free version of ESXi 3.5 will be locked back down again in the next release

Backup and Recovery

Since both versions of ESXi lack the Service Console the backup possibilities are limited. The following are some suggestions:

  • Use the VI Client Datastore browser to move copies of files
  • Use hardware mirror on local VMFS partition
  • Use a IP storage network such as a NAS filer to run VMs and leverage filer features for backup
  • Use backup agents within guest operating systems

updated 12.08.08 – Actually, the licensed version comes with VCB (in Foundation, Standard, and Enterprise). That’s the best way for doing backups. 3rd party products from Vizioncore and others also work with the free and VI versions.


As previously mentioned, managing ESXI with VirtualCenter and obtaining the VI Enterprise features requires purchasing licenses. The major point to understand here is that there is not a a la carte pricing model for features like VMotion, DRS, HA, or VCB. The best upgrade path for these enhancements with ESXi requires a purchase of the same versions VMware has been selling for ESX 3.5. Specifically, VI Foundation, VI Standard, and VI Enterprise. Unless I misunderstand, there does not seem to be a discount for using ESXi instead of ESX 3.5. There is an advantage of easier administration, tightened security, and an overall smaller footprint. The following VMware slide is a great visual of the differences between the versions and gives general list pricing as well. Click it for a larger version.

I used the following 2 primary resources to put this post together. Check out both for more information about the different versions and options of ESXi.

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  • rbrambley

    That'a bit tougher to answer.

    2 cpus is good. The more sockets and the more cores the more VMs you
    can run. Of course RAM and disk will also limit your guest density

    VMware has an onlline HCL. Google it and check your hardware there.
    That's what VMware supports. Yes, you can call them for support of
    your free ESXi too if you register your license. If it's not on the
    HCL they won't support it.

    Also google “esx or esxi whitebox”. These are community hardware lists
    that users maintain. They'll tell you if anyone has been successful
    running ESXi on your box. A lot of hardware not on the VMware HCL can
    run ESXi.

    Or, if you are really feeling adventerous, google “esx in a box” and
    decide if you want to learn ESXi while it's running as a VM in VMware
    Workstation, Fusion or Player. – but that might just blow your mind
    right now….

  • jlivens

    One point to add is that ESXi is difficult to troubleshoot if you have issues with hardware monitoring. I installed the HP version of ESXi 3.x and had trouble monitoring the hardware even though the HP drivers are included. I searched the web with no success and even reached out to a colleague at HP. Nothing worked and I eventually gave up. I am not sure if it was because of my old hardware (DL380 G3) or something else.

    Once I switched to ESX 3.5 and used the CLI to directly install the HP tools, everything worked perfectly. This problem may have been isolated to my old hardware, but could impact others. IMO, non-standard or whitebox hardware would benefit from the flexibility of the full CLI in ESX. Of course, the added cost for ESX may defeat the benefit.



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