VMware ESXi FAQs

vSphere ESXi is a bare-metal hypervisor that installs directly on top of your physical server and partitions it into multiple virtual machines.

What is the difference between the vSphere ESX and ESXi architectures?

VMware ESX® and VMware ESXi™ are both bare-metal hypervisor architectures that install directly on the server hardware. Both provide industry-leading performance and scalability; the difference resides in the architecture components and the operational management of the VMware vSphere® host. Although neither hypervisor architectures relies on an OS for resource management, the vSphere ESX architecture relied on a Linux operating system, called the Console OS (COS) or service console, to perform two management functions: executing scripts and installing third-party agents for hardware monitoring, backup or systems management. In the vSphere ESXi architecture, the service console has been removed, drastically reducing the hypervisor footprint and completing the ongoing trend of migrating management functionality from the local command line interface to remote management tools. The smaller code base of vSphere ESXi represents a smaller “attack surface” and less code to patch, improving reliability and security. The functionally of the service console is replaced by remote command line interfaces and adherence to system management standards.
View a detailed comparison of vSphere ESX and ESXi management.

Can I still deploy vSphere ESX or do I have to use vSphere ESXi?

Starting with vSphere 5, ESXi is the only hypervisor architecture option to deploy vSphere. vSphere ESXi’s smaller code base and lack of reliance on a general-purpose operating system makes it the more reliable and secure choice. Its compact design allows it to be embedded in mainstream physical servers for simpler and faster deployments. The vSphere ESXi architecture was designed with simplicity in mind. Its menu-driven startup and automatic configurations make it the easiest way to get started with VMware virtualization.

VMware recommends that customers migrate existing ESX architecture deployments to ESXi when upgrading to new versions of vSphere. Before migrating you should consider the following points:

  • Make sure your hardware is supported. Some older hardware supported by the ESX architecture is not supported with the newer ESXi architecture. Refer to the vSphere Hardware Compatibility List for information on supported hardware.
  • Make sure that your third-party management and backup tools are compatible with ESXi. Some tools may have a dependency on the service console (COS), which has been removed from the ESXi architecture. VMware has developed alternative integration points for ESXi and is actively engaged with backup and management partners to help them make the transition to the new architecture. Most major management or backup vendors such as IBM, BMC, CA, HP, EMC and Symantec offer products that are compatible with the new architecture, but you should check with your third-party vendor for the latest information on supported products and version numbers.

Does VMware still support the ESX architecture?

VMware will continue to provide technical support for the ESX architecture according to the VMware Product Lifecycle Policy.

What type of hardware is required to run vSphere with the ESXi architecture?

The ESXi hypervisor architecture is certified on over 1000 server systems and can run off certified USB keys on certain models. In general, new hardware systems supported by ESX will also be supported by ESXi, but please search the hardware compatibility lists for information about a specific hardware system.

What operating systems can I run on vSphere with the ESXi architecture?

VMware offers the broadest operating system support as compared to any other virtualization vendor. ESX and ESXi have virtually the same guest operating system support. Please search the guest operating system compatibility list for a full list of supported guest operating systems.

Can I run virtual machines created by Microsoft Virtual Server, Microsoft Virtual PC or VMware Server on VMware vSphere?

Yes. You can use the free VMware vCenter™ Converter™ to import virtual machines that were created using VMware vCenter Server™, Microsoft Virtual Server or Microsoft Virtual PC version 7 or higher. vCenter Converter also supports conversions from sources such as physical machines and certain third-party disk image formats.

How can I evaluate VMware vSphere?

The simplest way to evaluate vSphere is to download and install the free VMware vSphere Hypervisor Edition. Alternatively you can leverage the vSphere evaluations.

Will Update Manager patch my vSphere host when using the ESXi architecture?

VMware vCenter Update Manager™ will update hosts running ESXi. An update utility is also provided for environments where vCenter Update Manager is not present.

Note: vCenter Update Manager is not available for the free vSphere Hypervisor.

Does vSphere maintain log files or integrate with syslog when using the ESXi architecture?

Yes, using the ESXi architecture you can generate log files. Since vSphere 4.1, persistent logging is the default configuration. You can configure vSphere hosts to send logs to a file on a datastore as well as to a syslog server. For more information see the ESXi Management page.

Do the vCLI and PowerCLI work the same with both ESX and ESXi?

Most of the vCLI and PowerCLI commands work the same on both architectures. There are a few vCLI commands that are not applicable with ESX; these are outlined in Table 1-5 of the vCLI Reference Guide. There are also some specific differences in behavior between some vCLI commands and the equivalent COS commands; these are outlined in vSphere CLI and Service Console Parity Issues.

What is the ESXi Shell?

The ESXi Shell is a command-line based interface for diagnosis and repair of a vSphere host running ESXi. The ESXi Shell can be enabled and disabled through the DCUI or through vCenter Server, and can also be accessed remotely via SSH. For more information, see the ESXi Management page.

Is SSH supported on ESXi?

SSH access to the ESXi Shell is supported since version 4.1.

How do I run esxtop on a vSphere host?

"esxtop" functionality is provided by the vCLI command "resxtop," which has the same features as esxtop in the COS.

How do I monitor the hardware on vSphere host when using the ESXi hypervisor architecture?

vSphere supports both CIM APIs and SNMP v2/v3 for enabling hardware monitoring without installing agents. Hardware can be monitored via the vCenter console and via the major hardware monitoring tools from OEM vendors. See the ESXi Management page for more details.

How do I upgrade to ESXi or the latest version of vSphere?

Please visit the vSphere Upgrade Center.