Backup your ESXi configuration
There are many reasons that you would want to back up your ESXi configuration, of which the two main ones would be before upgrading to a new versions or for DR reasons.
If you are going to be upgrading an existing ESXi host to ESXi 5 you should backup your host configuration before proceeding. With vSphere 5 upgrades there is no option to roll back like there was with vSphere 4 upgrades. This means that a failed upgrade would require you to install ESXi 4.x and restore the configuration.
To backup an ESXi host you will need the vCLI installed on a server or you can also use the vMA.
# vicfg-cfgbackup –server ESXi_host_ip –-username username –-password password –-s backup_filename
Restore your ESXi configuration
Another really nice thing about ESXi is that it’s just as easy to restore your backed up configuration as it was to grab the backup. Simple install a clean version of ESXi matching the version that the backup was taken from. Connect to the host using vCLI or your vMA appliance as issue the restore command shown below.
# vicfg-cfgbackup –server ESXi_host_ip –-username username –-password password –-r backup_filename