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VMware ESXi (formerly ESX) is an enterprise-class, type-1 hypervisor developed by
VMware VMware, Inc. is an American cloud computing and virtualization technology company with headquarters in Palo Alto, California. VMware was the first commercially successful company to virtualize the x86 architecture. VMware's desktop software ru ...
for deploying and serving virtual computers. As a type-1 hypervisor, ESXi is not a
software application Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists ...
that is installed on an
operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
(OS); instead, it includes and integrates vital OS components, such as a
kernel Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine learnin ...
. After version 4.1 (released in 2010), VMware renamed ESX to ''ESXi''. ESXi replaces Service Console (a rudimentary operating system) with a more closely integrated OS. ESX/ESXi is the primary component in the
VMware Infrastructure VMware Infrastructure is a collection of virtualization products from VMware (a division of Dell Technologies). Virtualization is an abstraction layer that decouples hardware from operating systems. The VMware Infrastructure suite allows enterpri ...
software suite A software suite (also known as an application suite) is a collection of computer programs (application software, or programming software) of related functionality, sharing a similar user interface and the ability to easily exchange data with each ...
. The name ''ESX'' originated as an abbreviation of Elastic Sky X. In September 2004, the replacement for ESX was internally called ''VMvisor'', but later changed to ESXi (as the "i" in ESXi stood for "integrated").


Architecture

ESX runs on
bare metal In computer science, bare machine (or bare metal) refers to a computer executing instructions directly on logic hardware without an intervening operating system. Modern operating systems evolved through various stages, from elementary to the pre ...
(without running an operating system)"ESX Server Datasheet"
/ref> unlike other VMware products. It includes its own kernel. In the historic VMware ESX, a
Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...
was started first and then used to load a variety of specialized virtualization components, including ESX, which is otherwise known as the vmkernel component. The Linux kernel was the primary virtual machine; it was invoked by the service console. At normal run-time, the vmkernel was running on the bare computer, and the Linux-based service console ran as the first virtual machine. VMware dropped development of ESX at version 4.1, and now uses ESXi, which does not include a Linux kernel at all. The vmkernel is a
microkernel In computer science, a microkernel (often abbreviated as μ-kernel) is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system (OS). These mechanisms include low-level address space management, ...
with three interfaces: hardware, guest systems, and the service console (Console OS).


Interface to hardware

The vmkernel handles CPU and memory directly, using scan-before-execution (SBE) to handle special or privileged CPU instructionsGerstel, Markus: "Virtualisierungsansätze mit Schwerpunkt Xen"
and the SRAT (system resource allocation table) to track allocated memory. Access to other hardware (such as network or storage devices) takes place using modules. At least some of the modules derive from modules used in the
Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...
. To access these modules, an additional module called vmklinux implements the Linux module interface. According to the README file, "This module contains the Linux emulation layer used by the vmkernel." The vmkernel uses the device drivers: # net/e100 # net/e1000 # net/e1000e # net/bnx2 # net/tg3 # # net/pcnet32 # # scsi/adp94xx # scsi/aic7xxx # scsi/aic79xx # scsi/ips # scsi/lpfcdd-v732 # scsi/megaraid2 # scsi/mptscsi_2xx # scsi/qla2200-v7.07 # scsi/megaraid_sas # scsi/qla4010 # scsi/qla4022 # # scsi/aacraid_esx30 # scsi/lpfcdd-v7xx # scsi/qla2200-v7xx These drivers mostly equate to those described in VMware's
hardware compatibility list A hardware compatibility list (HCL) is a list of computer hardware (typically including many types of peripheral devices) that is compatible with a particular operating system or device management software. In today's world, there is a vast amount o ...
. All these modules fall under the
GPL The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general u ...
. Programmers have adapted them to run with the vmkernel: VMware Inc. has changed the module-loading and some other minor things.


Service console

In ESX (and not ESXi), the Service Console is a vestigial general purpose operating system most significantly used as bootstrap for the VMware kernel, vmkernel, and secondarily used as a management interface. Both of these Console Operating System functions are being deprecated from version 5.0, as VMware migrates exclusively to the ESXi model. The Service Console, for all intents and purposes, is the operating system used to interact with VMware ESX and the virtual machines that run on the server.


Purple Screen of Death

In the event of a hardware error, the vmkernel can catch a Machine Check Exception."KB: Decoding Machine Check Exception (MCE) output after a purple diagnostic screen , publisher=VMware, Inc."
/ref> This results in an error message displayed on a purple diagnostic screen. This is colloquially known as a purple diagnostic screen, or purple screen of death (PSoD, cf. blue screen of death (BSoD)). Upon displaying a purple diagnostic screen, the vmkernel writes debug information to the core dump partition. This information, together with the error codes displayed on the purple diagnostic screen can be used by VMware support to determine the cause of the problem.


Versions

VMware ESX used to be available in two main types: ESX and ESXi, but as of version 5, the original ESX has been discontinued in favor of ESXi. ESX and ESXi before version 5.0 do not support Windows 8/Windows 2012. These
Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washing ...
operating systems can only run on ESXi 5.x or later.VMware KBArticl
Windows 8/Windows 2012 doesn't boot on ESX
visited 12 September 2012
VMware ESXi, a smaller-footprint version of ESX, does not include the ESX Service Console. It is available - without the need to purchase a
vCenter vCenter Server is the centralized management utility for VMware, and is used to manage virtual machines, multiple ESXi VMware ESXi (formerly ESX) is an enterprise-class, type-1 hypervisor developed by VMware for deploying and serving v ...
license - as a free download from VMware, with some features disabled. ''ESXi'' stands for "ESX integrated". VMware ESXi originated as a compact version of VMware ESX that allowed for a smaller 32 MB disk footprint on the host. With a simple configuration console for mostly network configuration and remote based VMware Infrastructure Client Interface, this allows for more resources to be dedicated to the guest environments. Two variations of ESXi exist: * VMware ESXi Installable * VMware ESXi Embedded Edition The same media can be used to install either of these variations depending on the size of the target media. One can upgrade ESXi to
VMware Infrastructure VMware Infrastructure is a collection of virtualization products from VMware (a division of Dell Technologies). Virtualization is an abstraction layer that decouples hardware from operating systems. The VMware Infrastructure suite allows enterpri ...
3 or to
VMware vSphere VMware vSphere (formerly VMware Infrastructure 4) is VMware's cloud computing virtualization platform. It includes an updated vCenter Configuration Manager, as well as vCenter Application Discovery Manager, and the ability of vMotion to move m ...
4.0 ESXi. Originally named VMware ESX Server ESXi edition, through several revisions the ESXi product finally became VMware ESXi 3. New editions then followed: ESXi 3.5, ESXi 4, ESXi 5 and () ESXi 6.


GPL violation lawsuit

VMware has been sued by Christoph Hellwig, a Linux kernel developer. The lawsuit began on March 5, 2015. It was alleged that VMware had misappropriated portions of the Linux kernel, and, following a dismissal by the court in 2016, Hellwig announced he would file an appeal. The appeal was decided February 2019 and again dismissed by the German court, on the basis of not meeting "procedural requirements for the burden of proof of the plaintiff". In the last stage of the lawsuit in March 2019, the Hamburg Higher Regional Court also rejected the claim on procedural grounds. Following this, VMware officially announced that they would remove the code in question. This followed with Hellwig withdrawing his case, and withholding further legal action.


Related or additional products

The following products operate in conjunction with ESX: *
vCenter vCenter Server is the centralized management utility for VMware, and is used to manage virtual machines, multiple ESXi VMware ESXi (formerly ESX) is an enterprise-class, type-1 hypervisor developed by VMware for deploying and serving v ...
Server, enables monitoring and management of multiple ESX, ESXi and GSX servers. In addition, users must install it to run infrastructure services such as: ** vMotion (transferring virtual machines between servers on the fly whilst they are running, with zero downtime)VMware Blog by Kyle Gleed
vMotion: what's going on under the covers
25 February 2011, visited: 2 February 2012
VMware websit
vMotion brochure
. Retrieved 3 February 2012
** svMotion aka Storage vMotion (transferring virtual machines between Shared Storage LUNs on the fly, with zero downtime) ** Enhanced vMotion aka (a simultaneous vMotion and svMotion, supported on version 5.1 and above) ** Distributed Resource Scheduler (DRS) (automated vMotion based on host/VM load requirements/demands) ** High Availability (HA) (restarting of Virtual Machine Guest Operating Systems in the event of a physical ESX host failure) ** Fault Tolerance (FT) (almost instant stateful fail-over of a VM in the event of a physical host failure) * Converter, enables users to create VMware ESX Server- or Workstation-compatible virtual machines from either physical machines or from virtual machines made by other virtualization products. Converter replaces the VMware "P2V Assistant" and "Importer" products — P2V Assistant allowed users to convert physical machines into virtual machines, and Importer allowed the import of virtual machines from other products into VMware Workstation. * vSphere Client (formerly VMware Infrastructure Client), enables monitoring and management of a single instance of ESX or ESXi server. After ESX 4.1, vSphere Client was no longer available from the ESX/ESXi server but must be downloaded from the VMware web site.


Cisco Nexus 1000v

Network-connectivity between ESX hosts and the VMs running on it relies on virtual NICs (inside the VM) and virtual switches. The latter exists in two versions: the 'standard' vSwitch allowing several VMs on a single ESX host to share a physical NIC and the 'distributed vSwitch' where the on different ESX hosts together form one logical switch. Cisco offers in their
Cisco Nexus The Cisco Nexus series switches are modular and fixed port network switches designed for the data center. Cisco Systems introduced the Nexus Series of switches on January 28, 2008. The first chassis in the Nexus 7000 family is a 10-slot chassis ...
product-line the
Nexus 1000v The Cisco Nexus series switches are modular and fixed port network switches designed for the data center. Cisco Systems introduced the Nexus Series of switches on January 28, 2008. The first chassis in the Nexus 7000 family is a 10-slot chassis ...
, an advanced version of the standard distributed vSwitch. A Nexus 1000v consists of two parts: a supervisor module (VSM) and on each ESX host a virtual ethernet module (VEM). The VSM runs as a virtual appliance within the ESX cluster or on dedicated hardware (Nexus 1010 series) and the VEM runs as a module on each host and replaces a standard dvS (distributed virtual switch) from VMware. Configuration of the switch is done on the VSM using the standard
NX-OS NX-OS is a network operating system for the Nexus-series Ethernet switches and MDS-series Fibre Channel storage area network switches made by Cisco Systems. It evolved from the Cisco operating system SAN-OS, originally developed for its MDS swi ...
CLI CLI may refer to: Computing * Call Level Interface, an SQL database management API * Command-line interface, of a computer program * Command-line interpreter or command language interpreter; see List of command-line interpreters * CLI (x86 instruc ...
. It offers capabilities to create standard port-profiles which can then be assigned to virtual machines using vCenter. There are several differences between the standard dvS and the N1000v; one is that the Cisco switch generally has full support for network technologies such as LACP link aggregation or that the VMware switch supports new features such as routing based on physical NIC load. However, the main difference lies in the architecture: Nexus 1000v is working in the same way as a physical Ethernet switch does while dvS is relying on information from ESX. This has consequences for example in scalability where the Kappa limit for a N1000v is 2048 virtual ports against 60000 for a dvS. The Nexus1000v is developed in co-operation between Cisco and VMware and uses the
API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software Interface (computing), interface, offering a service to other pieces of software. A document or standa ...
of the dvS.Overview of th
Nexus 1000v
virtual switch, visited 9 July 2012


Third-party management tools

Because VMware ESX is a leader in the server-virtualization market, software and hardware vendors offer a range of tools to integrate their products or services with ESX. Examples are the products from
Veeam Software Veeam Software is a privately held US-based information technology company owned by Insight Partners that develops backup, disaster recovery and modern data protection software for virtual, physical and multi-cloud infrastructures. The company's ...
with backup and management applications and a plugin to monitor and manage ESX using
HP OpenView HP OpenView is the former name for a Hewlett-Packard product family that consisted of network and systems management products. In 2007, HP OpenView was rebranded as HP BTO (''Business Technology Optimization'') Software when it became part of the ...
,
Quest Software Quest Software, also known as Quest, is a privately held software company headquartered in Aliso Viejo, California, United States. Quest provides cloud management, software as a service, security, workforce mobility, and backup & recovery. The c ...
with a range of management and backup-applications and most major backup-solution providers have plugins or modules for ESX. Using Microsoft Operations Manager (SCOM) 2007/2012 with a Bridgeways ESX management pack gives the user a realtime ESX datacenter health view. Hardware vendors such as
Hewlett-Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components ...
and
Dell Dell is an American based technology company. It develops, sells, repairs, and supports computers and related products and services. Dell is owned by its parent company, Dell Technologies. Dell sells personal computers (PCs), servers, data ...
include tools to support the use of ESX(i) on their hardware platforms. An example is the ESX module for Dell's OpenManage management platform. VMware has added a Web Client since v5 but it will work on vCenter only and does not contain all features. vEMan is a Linux application which is trying to fill that gap. These are just a few examples: there are numerous 3rd party products to manage, monitor or backup ESX infrastructures and the VMs running on them.


Known limitations

As of September 2020, these are the known limitations of VMware ESXi 7.0 U1.


Infrastructure limitations

Some maximums in ESXi Server 7.0 may influence the design of data centers: * Guest system maximum RAM: 24 TB * Host system maximum RAM: 24 TB * Number of hosts in a
high availability High availability (HA) is a characteristic of a system which aims to ensure an agreed level of operational performance, usually uptime, for a higher than normal period. Modernization has resulted in an increased reliance on these systems. Fo ...
or Distributed Resource Scheduler cluster: 96 * Maximum number of processors per virtual machine: 768 * Maximum number of processors per host: 768 * Maximum number of virtual CPUs per physical
CPU core A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and ...
: 32 * Maximum number of virtual machines per host: 1024 * Maximum number of virtual CPUs per fault tolerant virtual machine: 8 * Maximum guest system RAM per fault tolerant virtual machine: 128 GB * VMFS5 maximum volume size: 64 TB, but maximum file size is 62 TB -512 bytes * Maximum Video memory per virtual machine: 4 GB


Performance limitations

In terms of performance, virtualization imposes a cost in the additional work the CPU has to perform to virtualize the underlying hardware. Instructions that perform this extra work, and other activities that require virtualization, tend to lie in operating system calls. In an unmodified operating system, OS calls introduce the greatest portion of virtualization "overhead".
Paravirtualization In computing, paravirtualization or para-virtualization is a virtualization technique that presents a software interface to the virtual machines which is similar, yet not identical, to the underlying hardware–software interface. The intent o ...
or other virtualization techniques may help with these issues. VMware developed the
Virtual Machine Interface Virtual may refer to: * Virtual (horse), a thoroughbred racehorse * Virtual channel, a channel designation which differs from that of the actual radio channel (or range of frequencies) on which the signal travels * Virtual function, a programming ...
for this purpose, and selected operating systems support this. A comparison between
full virtualization In computer science, virtualization is a modern technique developed in late 1990s and is different from simulation and emulation. Virtualization employs techniques used to create instances of an environment, as opposed to simulation, which model ...
and
paravirtualization In computing, paravirtualization or para-virtualization is a virtualization technique that presents a software interface to the virtual machines which is similar, yet not identical, to the underlying hardware–software interface. The intent o ...
for the ESX Server shows that in some cases paravirtualization is much faster.


Network limitations

When using the advanced and extended network capabilities by using the Cisco Nexus 1000v distributed virtual switch the following network-related limitations apply: :* 64 ESX/ESXi hosts per VSM (Virtual Supervisor Module) :* 2048 virtual ethernet interfaces per VMware vDS (virtual distributed switch) ::* and a maximum of 216 virtual interfaces per ESX/ESXi host :* 2048 active VLANs (one to be used for communication between VEMs and VSM) :* 2048 port-profiles :* 32 physical NICs per ESX/ESXi (physical) host :* 256 port-channels per VMware vDS (virtual distributed switch) ::* and a maximum of 8 port-channels per ESX/ESXi host


Fibre Channel Fabric limitations

Regardless of the type of virtual SCSI adapter used, there are these limitations: * Maximum of 4 Virtual SCSI adapters, one of which should be dedicated to virtual disk use * Maximum of 64 SCSI LUNs per adapter


See also

*
Comparison of platform virtualization software Platform virtualization software, specifically emulators and hypervisors, are software packages that emulate the whole physical computer machine, often providing multiple virtual machines on one physical platform. The table below compares basic i ...
* KVM Linux Kernel-based Virtual Machine – an open-source hypervisor platform * *
Hyper-V Microsoft Hyper-V, codenamed Viridian, and briefly known before its release as Windows Server Virtualization, is a native hypervisor; it can create virtual machines on x86-64 systems running Windows. Starting with Windows 8, Hyper-V superseded Win ...
– a competitor of VMware ESX from Microsoft *
Virtual appliance A virtual appliance is a pre-configured virtual machine image, ready to run on a hypervisor; virtual appliances are a subset of the broader class of software appliances. Installation of a software appliance on a virtual machine and packaging that i ...
*
Virtual disk image A disk image, in computing, is a computer file containing the contents and structure of a disk volume or of an entire data storage device, such as a hard disk drive, tape drive, floppy disk, optical disc, or USB flash drive. A disk image is usua ...
*
Virtual machine In computing, a virtual machine (VM) is the virtualization/emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized hardw ...
*
VMware ESXi compatible hardware Motherboards IOMMU Supported hardware including VMWare info can be found here too Lists of computer hardware {{compu-hardware-stub ...
*
VMware VMFS VMware VMFS (Virtual Machine File System) is VMware, Inc.'s clustered file system used by the company's flagship server virtualization suite, vSphere. It was developed to store virtual machine disk images, including snapshots. Multiple servers c ...
*
x86 virtualization x86 virtualization is the use of hardware-assisted virtualization capabilities on an x86/x86-64 CPU. In the late 1990s x86 virtualization was achieved by complex software techniques, necessary to compensate for the processor's lack of hardware-as ...
*
Xen Xen (pronounced ) is a type-1 hypervisor, providing services that allow multiple computer operating systems to execute on the same computer hardware concurrently. It was originally developed by the University of Cambridge Computer Laboratory an ...
– an open-source hypervisor platform


References


External links


VMware ESX product page

ESXi Release and Build Number History
{{DEFAULTSORT:Vmware Esx ESX