VMware ESX

VMware vSphere is a software for the U.S. company VMware Inc., which provides a virtual machine for x86 -64 -based hardware and their operating systems.


The software VMware vSphere is a so-called type 1 hypervisor, thus setting a bare metal hypervisor with 400 MB footprint certified by the manufacturer directly to the x86-64 hardware. It makes use of VMware both Linux and Open Source -based parts ( Grub bootloader, drivers for hardware such as network cards, chipset, storage, etc.) as well as the actual VMkernel, which contains proprietary technology.

Up to version 5.0 software is available both as slender bare metal hypervisor ( ESXi) as well as ESX version with a so-called console operating system to manage the hypervisor. With version 5.1 of this console operating system was abandoned and only offered the ESXi version.

VMware vSphere virtual machines stored in so-called datastores and there in directories. The key files are configuration files (*. Vmx) file and virtual hard disks (. Vmdk ). As datastores, NFS shares are used, or hard drives. The latter may be local disks or on a SAN (via HBA or iSCSI ) provided LUN. Hard Drives are formatted in creating a datastore using the VMware VMFS file system. This is a robust cluster- enabled file system which has been optimized for use by virtual machines. The current version has the number 5, the predecessor, VMFS 3 had restrictions associated with the block size and maximum volume size.

VMware vSphere is available in six editions (Essential, Essential Plus, Standard, Enterprise, and Enterprise Plus vSphere Desktop ). These differ besides the price through the provided functions, such as maximum number of virtual CPU, Storage API integration, automated load balancing, IO Control ( for network and storage) or distributed virtual switches. The Essential Editions are designed for small and medium-sized enterprises ( SME or SMB).

There is also a free version, called VMware hypervisor, with currently following important limitations per server, the restriction of a maximum of 32GB of RAM was removed in version 5.5:

  • Maximum 2 CPU sockets ( no limitations regarding cores)
  • Limited management ( vCenter, Scripting) and automation.

Detail functions

The following main functionalities enable a high degree of automation and a strong consolidation of resources.


To freeze the state of a virtual machine, and thus the ability to return to this state, for example in a test deployment of software and patches.


Requires the use of vCenter and shared storage (NFS, iSCSI, SAN). Provides uninterrupted procession of running virtual machines between different vSphere servers, for example, a necessary hardware maintenance or manual load balancing.

Storage vMotion

Requires the use of vCenter. Allows the relocation of belonging to a running virtual machine files. For example, from a data store ( datastore) on the same server or on any other shared storage on performance bottlenecks or pending maintenance.


High Availability (HA ) provides high availability by removing the corresponding virtual machines are automatically restarted on another available vSphere Host in case of failure of a host. The functionality requires the use of vCenter and shared storage.


FT (Fault Tolerance) allows in combination with the appropriate hardware and vCenter clustering of critical systems. The hardware resources are mirrored on two vSphere server and all commands are executed redundantly on the mirror server. If the master server, the slave takes over the further processing of the applications running in real time.


DRS ( Distributed Resource Scheduler) enables automatic load distribution in a managed with vCenter vSphere environment. Using vMotion virtual machines automatically postponed due to predefined rules between servers, server started or stopped when not in use.

Management Tools

The management of running the vSphere server can be done with the following VMware tools.

VSphere Client

The vSphere Client is a Windows application which allows interactive access to the resources of a vSphere server. Enables functions such as start / stop virtual machines, create / delete virtual machines, etc.

VSphere Web Client

Browser-based client, which will replace the vSphere Client in the near future. Requires the use of a corresponding server, which converts the instructions of the Web client.

VSphere Management Assistant

A Linux - based virtual management appliance that provides a command-line based administration tools.

SDK for clients

For management client under Linux (Perl ) and Windows ( PowerShell ) SDK can be installed which enable scripted access to the vSphere server.


Purchased separately VMware vCenter allows the full degree of inventory and automation. The functions vMotion, HA, FT, DRS require the use of vCenter.


In connection with the free edition VMware hypervisor also unsupported hardware is sometimes used. This is often called a " whitebox ". The challenge for the operation of a whitebox has fallen somewhat since the newer versions of vSphere, on the one hand older, stable motherboards ship with standard chipsets usually supported and on the other hand can be used for more exotic hardware (network cards ) and self-compiled OSS drivers are used.