The following methods are available to upgrade ESXi:
- Interactive upgrade: An interactive upgrade can be performed from the ESXi console to upgrade ESXi from an ESXi image on a CD/DVD-ROM or USB drive. To perform an interactive upgrade boot to the image on the CD-ROM or USB drive, follow the onscreen wizard to upgrade ESXi.
- Scripted upgrade: ESXi upgrades can be scripted by using a kickstart file. The default kickstart file is located in /etc/vmware/ks.cfg. The ks.cfg file allows the upgrade to be performed from a CD/DVD-ROM, USB, FTP server, NFS server, or HTTP/HTTPS server. Details about creating a ks.cfg file and automating the ESXi upgrade can be found in the VMware vSphere documentation for installing or upgrading hosts by using a script, which is located at http://pubs.vmware.com/vsphere-60/topic/com.vmware.vsphere.upgrade.doc/GUID-870A07BC-F8B4-47AF-9476-D542BA53F1F5.html.
- The command line with esxcli: esxcli can be used to upgrade ESXi from a depot or bundle by using the following command:
esxcli software vib install -d <FullPathToUpgradeDepot>
- vSphere Update Manager (VUM): Using VUM, an ESXi image is uploaded, an upgrade baseline is created, the baseline is applied to hosts, and the hosts are remediated against the baseline. The Designing a vSphere Update Manager deployment recipe in Chapter 4, vSphere Management Design, provides details about installing and using VUM to upgrade ESXi hosts.
- vSphere Auto Deploy: Hosts that are deployed using vSphere Auto Deploy can be reprovisioned by using a new image profile. Creating an ESXi 6 image profile is covered in the Creating a custom ESXi image recipe, from earlier in this chapter.
Any time that an ESXi upgrade is performed, it is important to verify compatibility on the VMware HCL. The host hardware and BIOS and the installed adapters should be verified with the list to ensure the stability of the host and the support of the environment. Verifying compatibility using the HCL is covered in the Using the VMware Hardware Compatibility List recipe, from earlier in this chapter.