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VMware ESXi/en


General information


  • VMware vSphere Hypervisor 5.x (ESXi) uses a filesystem called vmfs5 (formerly vmfs3), which uses GPT and supports drive sizes of up to 64 TiB (formerly 2 TiB).
  • Software RAID is not supported by ESXi.
  • The free version of ESXi supports a maximum of 32GB RAM.

Network configuration

  • VMware vSphere Hypervisor is an "operating system" designed for pure virtualization and supports neither NAT nor routing. Therefore, only a true bridged setup can be used.
  • To use a subnet an additional IP needs to be setup as a router VM.


  • The installation AND configuration of ESXi with the installation CD takes about 20-30 minutes, even without any prior knowledge. (Installation guide)


  • After installation the system has a test license, which expires after 60 days.
  • For the long-term usage of the OS a separate (free) license is required. This can be requested by registering on the VMware website
  • The license can be entered via the vSphere Client, under the tab "Configuration", the section "Software" and then under the menu item "Licensed functions". After selecting this you can click on the "Edit" button to the right and then enter the license key.

Hetzner specific information

Pre-built hardware

  • The EQ and EX servers are, aside from the EX 4, EX 4S, EX40 and EX 10, compatible with ESXi 5 and up. However, the hardware is not certified by VMware.
    • An installation on the EX 4 or EX 4S is possible if we install a compatible network card (NIC). This would cost 29 Euros once and the Flexi-Pack is required, which costs 15 Euros per month.
    • An installation on the EX10 is not possible, due to the 32GB RAM limitation of the free version and the unsupported onboard NIC.
  • Installing ESXi on the older DS or X servers is not possible.
  • When ordering a dedicated server, please state in the comments section at the end of the order form that you want ESXi on it. Hetzner support will then provide you with a CD and a remote console (LARA), through which you can install ESXi. This installation costs 25 Euros. In some cases our support will pre-install ESXi.
  • When installing on a server with multiple identical drives, ESXi can potentially show the drives in a different order than the BIOS does. Should the screen be blank with only a blinking cursor after the installation is done and you restart, try booting from the other drive.

Network Configuration

  • For connectivity between multiple ESXi servers within the same subnet, host routes via gateway are necessary due to network security restrictions.
host A
esxcfg-route -a <IP Host B> <Gateway IP>
host B
esxcfg-route -a <IP Host A> <Gateway IP>

Single IP addresses

  • IP addresses are, by default, statically mapped to the MAC address of the host. It is possible however to get separate MAC addresses for the additional single IPs via Robot. These can then be configured for the virtual machines. To get these MAC addresses assigned, log in to Robot, choose "Server" from the menu on the left, select the desired server, and then click on the "IPs" tab. Here you can click on the icon next to the single IP address to get a MAC address.



  • To use a subnet (IPv4 as well as IPv6) in ESXi, at least one additional single IP is required as a router VM, since ESXi itself cannot route. When ordering a subnet, please make sure to note that it is required for ESXi and should be routed on the additional single IP.

IMPORTANT Since IPv6 subnets are routed to link-local addresses (MAC-based), it is only possible to use IPv6 in a limited way (ie. in a single VM).


The confirmation email of the subnets contains (for example) the following information:

Below you will find the IP subnet added to your server
Subnet: /28
Usable IP addresses: to

You do NOT get a separate MAC for each IP from a subnet.


After ordering the IPv6 subnet you should receive an email after a short while with the following details:

Below you will find the IPv6 subnet added to your server #12345.
Subnet: 2a01:4f8:61:20e1::1 /64
Gateway: fe80::1
Usable IP addresses:
2a01:4f8:61:20e1::2 to 2a01:4f8:61:20e1:ffff:ffff:ffff:ffff

The IPv6 subnet is routed to the default link-local address (which is derived from the MAC address) of the main IP. Via Robot the routing of the IPv6 subnet can be switched to the link-local address of the virtual MAC (in other words, the additional single IP). This can be done in Robot, using the same symbol which is found next to additional single IPs to request virtual MAC addresses. The host system, so the ESXi itself, receives no IPv6 address. This is neither necessary nor possible because ESXi can not work with a fe80::1 gateway.

In order to use these IP addresses in virtual machines, a "router VM" supplemented by an additional NIC from the new subnet is necessary. The subnet itself requires a new vSwitch in ESXi to which all VMs in the subnet will be connected.


The network card type for the router VM should not be VMXNET2 or VMXNET3, as otherwise the TCP performance can be very bad. As a workaround LRO in the VM can be disabled via 'disable_lro=1'. More information on this bug can be found here: http://www.vmware.com/support/vsphere4/doc/vsp_esxi41_vc41_rel_notes.html

After an upgrade to VMware ESXi 5 this issue may appear again. You can address this issue by disabling Large Receive Offload (LRO) on the ESXi host:

  • Log into the ESXi host with the vSphere Client.
  • Select the host -> Configuration -> Software:Advanced Settings.
  • Select Net and scroll down slightly more than half way.
  • Set the following parameters from 1 to 0:

Reboot the ESXi host to activate these changes.

Preparations in the vSphere client

1. Create a vSwitch (in the example the name "subnetz" is used)

vSwitch part 1

vSwitch Part 2

vSwitch Part 3

vSwitch Part 4

2. Add a second NIC to the router VM. Connected network: subnetz (the previously created vSwitch)


3. The NIC of the virtual machine in the subnet. Connected network: subnetz

The networking overview should show the following:


Configuration of the Router VM

  • Example of /etc/network/interfaces on the router VM
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
# WAN-NIC im VMnetwork
auto eth0
iface eth0 inet dhcp
# for the IPv6 subnet the configuration is analog to other virtualisations
iface eth0 inet6 static
  address 2a01:4f8:61:20e1::2
  netmask 128
  gateway fe80::1
# LAN NIC in Subnet
auto eth1
iface eth1 inet static
# The prefix/netmask can/must be changed according to the amount of network
# segments
iface eth1 inet6 static
  address    2a01:4f8:61:20e1::2
  netmask    64
  • Example of /etc/network/interfaces of a Linux VM in the subnet
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet static

The router VM is now connected to both networks and can be used as a gateway for virtual machines in the subnet. Don't forget to activate IP forwarding in the kernel:

echo 1 > /proc/sys/net/ipv4/ip_forward
echo 1 > /proc/sys/net/ipv6/conf/all/forwarding

To make this persistent across reboots, add the following line to /etc/sysctl.conf


The virtual machines should now be accessible (via SSH for example) via their assigned IPs.

Installation guide

  • During the order choose the desired server (the EX10 is not supported by the free version). A RAID controller can be optionally added if desired (requires the Flexi-Pack) and is supported during the installation.
  • Choose the "Rescue System" as the OS.
  • Once the server is online (you will get an email from us informing you of this) you can order a LARA remote console and make a note that you want to install ESXi, as well as confirming the additional cost of 25 Euros.
  • Once you get the login details for the LARA connect to it and install ESXi.

Afterwards, the following screen should be displayed:

ESXi installed

  • After a reboot login using the password that you entered during the installation. This is the root password for SSH as well as the password for the VMware vSphere Client (requires Windows). This can then be downloaded separately via a browser.


  • After successful installation you can order up to three additional single IP addresses via Robot. You can get a MAC address for your additional single IP through Robot under the "IPs" tab. You will see a small button next to the IP address. Clicking on that button will give the IP address a virtual MAC.
  • Configure the MAC addresses of the virtual servers with the corresponding IP addresses through vSphere. Once this is done even DHCP will work via the Hetzner network!

For additional information regarding ESXi and its usage, please refer to the official website

Manual installation of updates

The installation of updates in the free version can only be done via the console or via VMware Go. An update can be several hundred megabytes, which can take a long time with a standard DSL connection, which is why the following guide can help. This is done at your own risk. There is no warranty or guarantee for correctness!

Prequisite is SSH activated access and that the system is in maintenance mode. This can be activated via:

vim-cmd hostsvc/maintenance_mode_enter

Updating VSphere 5.0 to 5.1

First of all the VMware-ESXi-5.1.0-799733-depot.zip update needs to be downloaded from the VMWare Updates Page, or, used at your own risk and without warranty or liability, from the Hetzner Download Page and saved on the ESXi Host.

Once all the VMs have been shut down and the system has entered the maintenance mode via "vim-cmd hostsvc/maintenance_mode_enter", the update can be installed in two ways. The following command refreshes the system and removes all the packages that are not included in the update. This is equivalent to a new installation.

esxcli software profile install -d /vmfs/volumes/datastore1/VMware-ESXi-5.1.0-799733-depot.zip -p ESXi-5.1.0-799733-standard

Alternatively, only the packages containted in the update can be updated to their new versions, leaving all other packages intact.

esxcli software profile update -d /vmfs/volumes/datastore1/VMware-ESXi-5.1.0-799733-depot.zip -p ESXi-5.1.0-799733-standard

Finally, the system must be rebooted. When the VMs are turned on for the first time after the reboot, it is possible that a message appears noting that the VM was copied or moved. This happens because the UUIDs get changed during the update. You can safely select "VM was moved" in this situation. See also: VMware Help Page

Installation of Patches

After the patches have been transferred onto the system, they can be installed. It is important that the full path name is entered, eg.:

esxcli software vib install --depot="/vmfs/volumes/datastore1/patches/ESXi510-201210001.zip"
Installation Result
Message: The update completed successfully, but the system needs to be rebooted for the changes to be effective.
Reboot Required: true

After a reboot the maintenance mode needs to be exited:

vim-cmd hostsvc/maintenance_mode_exit

Monitoring RAID controller

For the 3ware controller there exists both a CIM Provider as well as a CLI. The 64-bit CLI for Linux can be used from version 9.5.2 onwards.

Note: 3ware controllers are only supported by ESXi 5.0 via an external driver.

For Adaptec controllers the CIM Provider and the CLI (arcconf) must be manually installed. Required is an up-to-date version of the driver. An installation guide can be found on the Adaptec site (PDF)

Monitoring can be achieved through the installation of remote ARCCONF via a Windows/Linux system.

$ arcconf GETCONFIG 1 AD

Parallel operation of onboard controller/hardware RAID

During the installation ESXi only "sees" one type of storage, so either the onboard SATA controller or an additional RAID controller. If drives are connected to both then the hardware controller ist prioritized and the drives connected to the onboard controller are invisible. By manually loading the appropriate kernel module these drives can still be used.

/sbin/vmkload_mod ahci

To have this module loaded automatically during start, the line above must be added to /etc/rc.local and /sbin/auto-backup.sh.

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