• This article does not include the steps for installing ESXi 5.5. For more information about installing ESXi 5.5 best practices, see Installing or upgrading to ESXi 5.5 best practices (2052329).
• This article assumes that you have read the documentation for the update you are applying. For more information, see the VMware vSphere 5.5 Release Notes and the vSphere Upgrade Guide. The documentation contains definitive information. If there is a discrepancy between the guide and this article, assume that the guide is correct.

Methods of installing

• Interactive ESXi installation
• Scripted ESXi Installation
• Auto Deploy ESXi Installation
• Customizing Installations with ESXi Image Builder CLI

Interactive ESXi installation

Interactive installations are recommended for small deployments of fewer than five hosts.

You boot the installer from a CD or DVD, from a bootable USB device, or by PXE booting the installer from a location on the network, then follow the prompts in the installation wizard to install ESXi to disk.

In a typical interactive installation, you boot the ESXi installer and respond to the installer prompts to install ESXi to the local host disk. The installer reformats and partitions the target disk and installs the ESXi boot image. If you have not installed ESXi on the target disk before, all data located on the drive is overwritten, including hardware vendor partitions, operating system partitions, and associated data. For further information, see the Interactive ESXi Installation section in the vSphere Installation and Setup Guide.

Caution: To ensure that you do not lose any data, migrate the data to another machine before you install ESXi.

Scripted ESXi installation

Running a script is an efficient way to deploy multiple ESXi hosts with an unattended installation.

The installation script contains the host configuration settings. You can use the script to configure multiple hosts with the same settings. For more information, see the Installing, Upgrading, or Migrating Hosts Using a Script in the vSphere Installation and Setup Guide.

Auto Deploy ESXi installation

vSphere 5.5 provides several ways to install ESXi with Auto Deploy.

• Provisioning ESXi hosts using vSphere Auto Deploy.
  
  With the vSphere Auto Deploy ESXi feature, you can provision and reprovision large numbers of ESXi hosts efficiently with vCenter Server.
  
  When you provision hosts using the Auto Deploy feature, vCenter Server loads the ESXi image directly into the host memory. Auto Deploy does not store the ESXi state on the host disk. vCenter Server makes image profiles with ESXi updates and patches available for download through an image profile and, optionally, the host configuration through a host profile. You can create host profiles using the vSphere Client. You can create custom image profiles with ESXi Image Builder CLI. For more information, see the Using vSphere ESXi Image Builder CLI and vSphere Host Profiles section in the vSphere Installation and Setup Guide.
  
  For more information on provisioning ESXi hosts using vSphere Auto Deploy, see the Understanding vSphere Auto Deploy section in vSphere Installation and Setup Guide.
  
  
• Using vSphere Auto Deploy for Stateful Installations.
  
  In some situations, it is useful to provision hosts with Auto Deploy and perform all subsequent boots from disk.
  
  vSphere Auto Deploy can be used to provision an ESXi host and set up a host profile that causes the host to store the ESXi image and configuration on the local disk, a remote disk, or a USB drive. Subsequently, the ESXi host boots from this local image. Auto Deploy no longer provisions the host. This process is similar to performing a scripted installation. With a scripted installation, the script provisions a host and the host then boots from disk. In this case, Auto Deploy provisions a host and the host then boots from disk.
  
  For more information see the Using Auto Deploy for Stateless Caching and Stateful Installs section in the vSphere Installation and Setup Guide.
  
  
• vSphere Auto Deploy and Stateless Caching.
  
  vSphere Auto Deploy can be used to provision an ESXi host and set up a host profile that causes the host to store the ESXi image and configuration on the local disk, a remote disk, or a USB drive.
  
  Subsequently, the Auto Deploy server continues to provision this host. If the Auto Deploy server is not available, the host uses the image on disk.
  
  For more information see the Using Auto Deploy for Stateless Caching and Stateful Installs section in the vSphere Installation and Setup Guide.

Customizing installations with ESXi Image Builder CLI

You can use ESXi Image Builder CLI to create ESXi installation images with a customized set of updates, patches, and drivers.

ESXi Image Builder CLI is a PowerShell CLI command set that you can use to create an ESXi installation image with a customized set of ESXi updates and patches. You can also include third-party network or storage drivers that are released between vSphere releases.

• Burning it to an installation DVD
• Through vCenter Server, using the Auto Deploy feature

For more information, see the Using vSphere ESXi Image Builder CLI and Installing ESXi Using vSphere Auto Deploy section in the vSphere Installation and Setup Guide.