The below process could be used to mount a datastore for recovery purposes. In most cases if one has an ESXi install that can’t boot, using the repair option on the install CD or booting ESXi with from a USB stick may be the way to go. But if you need a quick way to access a VMFS datastore to copy files from it, you can use the below process.
A change with ESXi 4.0 was to enable networking during the install process. This process assumes that the host is able to obtain an IP address on your network. If you don’t have a DHCP server but a NIC that ESXi can use, then you would need to use esxcfg-vmknic to assign an IP address to the host.
1) Boot from the install CD and once you’re at one of the menu screens, press ALT+F1 to switch to the console. Login with the user root – password is blank. You’ll first want to run ls /vmfs/devices/disks/ to ensure that the running instance of ESXi can see the host’s physical disks. In the below image the default partitions from an ESXi install to a single HD can be seen. Nothing is mounted under /vmfs/volumes/.
2) The first step to this process is to load the vmfs3 driver with the vmkload_mod command. You can use vmkload_mod -l to see which modules are currently loaded.
3) The second step is to run vmkfstools -V. This will mount any existing VMFS datastores
You can then enable SSH or use scp at the console to copy files from the datastore to another network location.