You can use the System Cache Configuration host profile to provision hosts with vSphere Auto Deploy stateless caching and stateful installs.

Examples of Stateless Caching and Stateful Installs

Hosts provisioned with vSphere Auto Deploy cache the image (stateless caching)
Set up and apply a host profile for stateless caching. You can cache the image on a local disk, a remote disk, or a USB drive. Continue provisioning this host with vSphere Auto Deploy. If the vSphere Auto Deploy server becomes unavailable, for example because hundreds of hosts attempt to access it simultaneously, the host boots from the cache. The host attempts to reach the vSphere Auto Deploy server after the boot operation to complete configuration.
Hosts provisioned with vSphere Auto Deploy become stateful hosts
Set up and apply a host profile for stateful installs. When you provision a host with vSphere Auto Deploy, the image is installed on the local disk, a remote disk, or a USB drive. For subsequent boots, you boot from the disk. The host no longer uses vSphere Auto Deploy.

Preparation

To successfully use stateless caching or stateful installs, decide how to configure the system and set the boot order.

Table 1. Preparation for Stateless Caching or Stateful Installs
Requirement or Decision Description
Decide on VMFS partition overwrite

When you install ESXi by using the interactive installer, you are prompted whether you want to overwrite an existing VMFS datastore. The System Cache Configuration host profile provides an option to overwrite existing VMFS partitions.

The option is not available if you set up the host profile to use a USB drive.

Decide whether you need a highly available environment If you use vSphere Auto Deploy with stateless caching, you can set up a highly available vSphere Auto Deploy environment to guarantee that virtual machines are migrated on newly provisioned hosts and that the environment supports vNetwork Distributed Switch even if the vCenter Server system becomes temporarily unavailable.
Set the boot order

The boot order you specify for your hosts depends on the feature you want to use.

  • To set up vSphere Auto Deploy with stateless caching, configure your host to first attempt to boot from the network, and to then attempt to boot from disk. If the vSphere Auto Deploy server is not available, the host boots using the cache.
  • To set up vSphere Auto Deploy for stateful installs on hosts that do not currently have a bootable disk, configure your hosts to first attempt to boot from disk, and to then attempt to boot from the network.
    Note: If you currently have a bootable image on the disk, configure the hosts for one-time PXE boot, and provision the host with vSphere Auto Deploy to use a host profile that specifies stateful installs.

Stateless Caching and Loss of Connectivity

If the ESXi hosts that run your virtual machines lose connectivity to the vSphere Auto Deploy server, the vCenter Server system, or both, some limitations apply the next time you reboot the host.

  • If vCenter Server is available but the vSphere Auto Deploy server is unavailable, hosts do not connect to the vCenter Server system automatically. You can manually connect the hosts to the vCenter Server, or wait until the vSphere Auto Deploy server is available again.
  • If both vCenter Server and vSphere Auto Deploy are unavailable, you can connect to each ESXi host by using the VMware Host Client, and add virtual machines to each host.
  • If vCenter Server is not available, vSphere DRS does not work. The vSphere Auto Deploy server cannot add hosts to the vCenter Server. You can connect to each ESXi host by using the VMware Host Client, and add virtual machines to each host.
  • If you make changes to your setup while connectivity is lost, the changes are lost when the connection to the vSphere Auto Deploy server is restored.