How vSphere 5.0 Differs from vSphere 4.x
Service Console is removed
The graphical installer relied on the Service Console, which is not a part of ESXi. ESXi retains the text-based installer
Before ESXi 5.0, ESXi was installed on the physical disk of each ESXi host. With ESXi 5.0, you can load an ESXi image directly into memory by using vSphere Auto Deploy. You can provision and reprovision large numbers of ESXi hosts efficiently with vCenter Server, and manage ESXi updates and patching by using an image profile. You can save host configuration such as network or storage setup as a host profile and apply it to the host by using Auto Deploy. You can use ESXi Image Builder CLI to create ESXi installation images with a customized set of updates, patches, and drivers.
ESXi 5.0 uses a single installer wizard for fresh installations and upgrades.
The vihostupdate and esxupdate utilities are not supported for ESXi 5.0. You cannot upgrade or migrate to ESXi 5.0 by using any command-line utility. After you have upgraded or migrated to
ESXi 5.0, you can upgrade or patch ESXi 5.0 hosts using vCLI esxcli commands.
IMPORTANT After you upgrade or migrate your host to ESXi 5.0, you cannot roll back to your version 4.x ESX or ESXi software. Back up your host before you perform an upgrade or migration, so that, if the upgrade or migration fails, you can restore your 4.x host.
Installer Caching Instead of using a binary image to install the system, whatever bits were used at boot time are cached to the system. This caching reduces installation problems caused by accessing installation files across networks that are under load.
Changes to partitioning of host disks All freshly installed hosts in vSphere 5.0 use the GUID Partition Table format instead of the MSDOS-style partition label. This change supports ESXi installation on disks larger than 2TB.
Newly installed vSphere 5.0 hosts use VMFS5, an updated version of the VMware File System for vSphere 5.0. Unlike earlier versions, ESXi 5.0 does not create VMFS partitions in second and successive disks. Upgraded systems do not use GUID Partition Tables (GPT), but retain the older MSDOS-based partition label.