4. Resource Group Architecture : 4.1 Compute Resources : 4.1.1 Stateless ESXi
4.1.1 Stateless ESXi
Stateless ESXi refers to running VMware ESXi™ software on a host entirely in memory, with no local persistence data. Centralizing management of the host state enables consistent configuration over large sets of similar hosts and rapid provisioning of vSphere hosts. This helps to improve operational efficiency in large-scale vCloud environments.
Stateless ESXi requires VMware vSphere Auto Deploy™, a deployment server that applies the image profile and host profile to the PXE-booted hosts. Install vSphere Auto Deploy on a standalone host or on the vCenter Server instance. vSphere Auto Deploy is installed by default on the vCenter Server virtual appliance. Install VMware vSphere PowerCLI™ in a location that vCenter and vSphere Auto Deploy can both reach. The host profile is essential to the stateless environment, as every reboot of a server clears the host of any local configuration data.
Configure all stateless vSphere hosts for DHCP. The DHCP server requires configuration changes to direct the vSphere host to a TFTP server. The server can be a separate DHCP server or it can be the organization’s DHCP server. The vCenter Server virtual appliance includes DHCP and TFTP services.
Identify an image profile to use for vCloud hosts. This can be a profile stored in a public depot or a zipped file stored locally. If using host profiles, save a copy of the host profile to a location accessible by vSphere Auto Deploy and add rules to the rules engine using VMware vSphere® ESXi™ Image Builder CLI.
Figure 7. Auto Deploy First Boot
vCloud Director can manage stateful or stateless vSphere hosts. If you choose the stateless option, add the vCloud Director vSphere Installation Bundle (VIB) (which contains the agent) to the image profile. The vCloud Director VIB is loaded automatically when the host boots up. For preparation and unpreparation of stateless hosts, vCloud Director configures the agent using a host profile with an associated answer file.
If the host is rebooted, the appropriate image profile is reloaded when the host starts back up. vCloud Director detects the state change, and the configuration is pushed again to the host.
If using stateless mode, avoid creating designs that require host-specific configuration. When converting a prepared stateful host to stateless, unprepare hosts prior to the conversion.