The System Cache Configuration host profile supports stateless caching and stateful installs.

Stateless caching is a good solution when you use the Auto Deploy infrastructure, but you require a safeguard in case the Auto Deploy server is unavailable. Hosts provisioned with stateless caching host profile settings continue to be provisioned with Auto Deploy. Stateful installs support network installation through Auto Deploy. After the initial installation, hosts that are provisioned with stateful install host profile settings will boot from disk.

Use Cases

The System Cache Configuration host profile supports the following use cases.

Hosts provisioned with 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 Auto Deploy. If the Auto Deploy server becomes unavailable, the host boots from the cache.

Hosts provisioned with Auto Deploy become stateful hosts

Set up and apply a host profile for stateful installs. When you provision a host with Auto Deploy, the image is installed on the local disk, a remote disk, or a USB drive. For subsequent boots, you boot from disk. The host no longer uses Auto Deploy.

Preparation

To successfully use stateless caching or stateful installs, decide how to set up 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 with the interactive installer, you are prompted whether you want to overwrite an existing VMFS datastore. The System Cache Configuration host profile allows you to overwrite existing VMFS partitions by selecting a check box.

The check box 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 Auto Deploy with stateless caching, you can set up a highly available 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 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 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 Auto Deploy is not available, the host boots using the cache.

  • To set up 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 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 Auto Deploy server, the vCenter Server system, or both, some limitations apply when you next reboot.

  • If vCenter Server is available but the Auto Deploy server is unavailable, hosts do not connect to the vCenter Server automatically. You can manually connect the hosts to the vCenter Server, or wait until the Auto Deploy server is available again.

  • If both vCenter Server and vSphere Auto Deploy do not work, you can connect to each ESXi host by using the vSphere Client, and assign virtual machines to each host.

  • If vCenter Server is not available, vSphere DRS does not work. The Auto Deploy server cannot add hosts to the vCenter Server system. You can connect to each ESXi host by using the vSphere Client, and assign virtual machines to each host.

  • If you make changes to your setup while connectivity is lost, you lose these changes when the Auto Deploy server is restored after the outage.