<s>
VMware	B-Operating_System
ESXi	I-Operating_System
(	O
formerly	O
ESX	O
)	O
is	O
an	O
enterprise-class	B-Application
,	O
type-1	O
hypervisor	B-Operating_System
developed	O
by	O
VMware	O
for	O
deploying	O
and	O
serving	B-Application
virtual	B-Architecture
computers	I-Architecture
.	O
</s>
<s>
As	O
a	O
type-1	O
hypervisor	B-Operating_System
,	O
ESXi	B-Operating_System
is	O
not	O
a	O
software	B-Application
application	I-Application
that	O
is	O
installed	O
on	O
an	O
operating	B-General_Concept
system	I-General_Concept
(	O
OS	O
)	O
;	O
instead	O
,	O
it	O
includes	O
and	O
integrates	O
vital	O
OS	O
components	O
,	O
such	O
as	O
a	O
kernel	B-Operating_System
.	O
</s>
<s>
After	O
version	O
4.1	O
(	O
released	O
in	O
2010	O
)	O
,	O
VMware	O
renamed	O
ESX	O
to	O
ESXi	B-Operating_System
.	O
</s>
<s>
ESXi	B-Operating_System
replaces	O
Service	O
Console	O
(	O
a	O
rudimentary	O
operating	B-General_Concept
system	I-General_Concept
)	O
with	O
a	O
more	O
closely	O
integrated	O
OS	O
.	O
</s>
<s>
ESX/ESXi	O
is	O
the	O
primary	O
component	O
in	O
the	O
VMware	B-Application
Infrastructure	I-Application
software	B-Application
suite	I-Application
.	O
</s>
<s>
In	O
September	O
2004	O
,	O
the	O
replacement	O
for	O
ESX	O
was	O
internally	O
called	O
VMvisor	O
,	O
but	O
later	O
changed	O
to	O
ESXi	B-Operating_System
(	O
as	O
the	O
"	O
i	O
"	O
in	O
ESXi	B-Operating_System
stood	O
for	O
"	O
integrated	O
"	O
)	O
.	O
</s>
<s>
ESX	O
runs	O
on	O
bare	O
metal	O
(	O
without	O
running	O
an	O
operating	B-General_Concept
system	I-General_Concept
)	O
unlike	O
other	O
VMware	O
products	O
.	O
</s>
<s>
It	O
includes	O
its	O
own	O
kernel	B-Operating_System
.	O
</s>
<s>
In	O
the	O
historic	O
VMware	B-Operating_System
ESX	I-Operating_System
,	O
a	O
Linux	B-Operating_System
kernel	I-Operating_System
was	O
started	O
first	O
and	O
then	O
used	O
to	O
load	O
a	O
variety	O
of	O
specialized	O
virtualization	O
components	O
,	O
including	O
ESX	O
,	O
which	O
is	O
otherwise	O
known	O
as	O
the	O
vmkernel	O
component	O
.	O
</s>
<s>
The	O
Linux	B-Operating_System
kernel	I-Operating_System
was	O
the	O
primary	O
virtual	B-Architecture
machine	I-Architecture
;	O
it	O
was	O
invoked	O
by	O
the	O
service	O
console	O
.	O
</s>
<s>
At	O
normal	O
run-time	O
,	O
the	O
vmkernel	O
was	O
running	O
on	O
the	O
bare	O
computer	O
,	O
and	O
the	O
Linux-based	O
service	O
console	O
ran	O
as	O
the	O
first	O
virtual	B-Architecture
machine	I-Architecture
.	O
</s>
<s>
VMware	O
dropped	O
development	O
of	O
ESX	O
at	O
version	O
4.1	O
,	O
and	O
now	O
uses	O
ESXi	B-Operating_System
,	O
which	O
does	O
not	O
include	O
a	O
Linux	B-Operating_System
kernel	I-Operating_System
at	O
all	O
.	O
</s>
<s>
The	O
vmkernel	O
is	O
a	O
microkernel	B-Operating_System
with	O
three	O
interfaces	O
:	O
hardware	O
,	O
guest	O
systems	O
,	O
and	O
the	O
service	O
console	O
(	O
Console	O
OS	O
)	O
.	O
</s>
<s>
At	O
least	O
some	O
of	O
the	O
modules	O
derive	O
from	O
modules	O
used	O
in	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
.	O
</s>
<s>
To	O
access	O
these	O
modules	O
,	O
an	O
additional	O
module	O
called	O
vmklinux	O
implements	O
the	O
Linux	B-Operating_System
module	O
interface	O
.	O
</s>
<s>
According	O
to	O
the	O
README	O
file	O
,	O
"	O
This	O
module	O
contains	O
the	O
Linux	B-Operating_System
emulation	O
layer	O
used	O
by	O
the	O
vmkernel.	O
"	O
</s>
<s>
These	O
drivers	O
mostly	O
equate	O
to	O
those	O
described	O
in	O
VMware	O
's	O
hardware	B-Device
compatibility	I-Device
list	I-Device
.	O
</s>
<s>
All	O
these	O
modules	O
fall	O
under	O
the	O
GPL	B-License
.	O
</s>
<s>
In	O
ESX	O
(	O
and	O
not	O
ESXi	B-Operating_System
)	O
,	O
the	O
Service	O
Console	O
is	O
a	O
vestigial	O
general	O
purpose	O
operating	B-General_Concept
system	I-General_Concept
most	O
significantly	O
used	O
as	O
bootstrap	O
for	O
the	O
VMware	O
kernel	B-Operating_System
,	O
vmkernel	O
,	O
and	O
secondarily	O
used	O
as	O
a	O
management	O
interface	O
.	O
</s>
<s>
Both	O
of	O
these	O
Console	O
Operating	B-General_Concept
System	I-General_Concept
functions	O
are	O
being	O
deprecated	O
from	O
version	O
5.0	O
,	O
as	O
VMware	O
migrates	O
exclusively	O
to	O
the	O
ESXi	B-Operating_System
model	O
.	O
</s>
<s>
The	O
Service	O
Console	O
,	O
for	O
all	O
intents	O
and	O
purposes	O
,	O
is	O
the	O
operating	B-General_Concept
system	I-General_Concept
used	O
to	O
interact	O
with	O
VMware	B-Operating_System
ESX	I-Operating_System
and	O
the	O
virtual	B-Architecture
machines	I-Architecture
that	O
run	O
on	O
the	O
server	O
.	O
</s>
<s>
VMware	B-Operating_System
ESX	I-Operating_System
used	O
to	O
be	O
available	O
in	O
two	O
main	O
types	O
:	O
ESX	O
and	O
ESXi	B-Operating_System
,	O
but	O
as	O
of	O
version	O
5	O
,	O
the	O
original	O
ESX	O
has	O
been	O
discontinued	O
in	O
favor	O
of	O
ESXi	B-Operating_System
.	O
</s>
<s>
ESX	O
and	O
ESXi	B-Operating_System
before	O
version	O
5.0	O
do	O
not	O
support	O
Windows	O
8/Windows	O
2012	O
.	O
</s>
<s>
These	O
Microsoft	O
operating	B-General_Concept
systems	I-General_Concept
can	O
only	O
run	O
on	O
ESXi	B-Operating_System
5.x	O
or	O
later	O
.	O
</s>
<s>
VMware	B-Operating_System
ESXi	I-Operating_System
,	O
a	O
smaller-footprint	O
version	O
of	O
ESX	O
,	O
does	O
not	O
include	O
the	O
ESX	O
Service	O
Console	O
.	O
</s>
<s>
It	O
is	O
available	O
-	O
without	O
the	O
need	O
to	O
purchase	O
a	O
vCenter	B-Application
license	O
-	O
as	O
a	O
free	O
download	O
from	O
VMware	O
,	O
with	O
some	O
features	O
disabled	O
.	O
</s>
<s>
ESXi	B-Operating_System
stands	O
for	O
"	O
ESX	O
integrated	O
"	O
.	O
</s>
<s>
VMware	B-Operating_System
ESXi	I-Operating_System
originated	O
as	O
a	O
compact	O
version	O
of	O
VMware	B-Operating_System
ESX	I-Operating_System
that	O
allowed	O
for	O
a	O
smaller	O
32MB	O
disk	O
footprint	O
on	O
the	O
host	O
.	O
</s>
<s>
With	O
a	O
simple	O
configuration	O
console	O
for	O
mostly	O
network	O
configuration	O
and	O
remote	O
based	O
VMware	B-Application
Infrastructure	I-Application
Client	O
Interface	O
,	O
this	O
allows	O
for	O
more	O
resources	O
to	O
be	O
dedicated	O
to	O
the	O
guest	O
environments	O
.	O
</s>
<s>
Two	O
variations	O
of	O
ESXi	B-Operating_System
exist	O
:	O
</s>
<s>
One	O
can	O
upgrade	O
ESXi	B-Operating_System
to	O
VMware	B-Application
Infrastructure	I-Application
3	I-Application
or	O
to	O
VMware	B-Application
vSphere	I-Application
4.0	O
ESXi	B-Operating_System
.	O
</s>
<s>
Originally	O
named	O
VMware	B-Operating_System
ESX	I-Operating_System
Server	I-Operating_System
ESXi	B-Operating_System
edition	O
,	O
through	O
several	O
revisions	O
the	O
ESXi	B-Operating_System
product	O
finally	O
became	O
VMware	B-Operating_System
ESXi	I-Operating_System
3	O
.	O
</s>
<s>
VMware	O
has	O
been	O
sued	O
by	O
Christoph	O
Hellwig	O
,	O
a	O
Linux	B-Operating_System
kernel	I-Operating_System
developer	O
.	O
</s>
<s>
It	O
was	O
alleged	O
that	O
VMware	O
had	O
misappropriated	O
portions	O
of	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
</s>
<s>
vCenter	B-Application
Server	O
,	O
enables	O
monitoring	O
and	O
management	O
of	O
multiple	O
ESX	O
,	O
ESXi	B-Operating_System
and	O
GSX	O
servers	O
.	O
</s>
<s>
Converter	O
,	O
enables	O
users	O
to	O
create	O
VMware	B-Operating_System
ESX	I-Operating_System
Server	I-Operating_System
-	O
or	O
Workstation-compatible	O
virtual	B-Architecture
machines	I-Architecture
from	O
either	O
physical	O
machines	O
or	O
from	O
virtual	B-Architecture
machines	I-Architecture
made	O
by	O
other	O
virtualization	O
products	O
.	O
</s>
<s>
Converter	O
replaces	O
the	O
VMware	O
"	O
P2V	O
Assistant	O
"	O
and	O
"	O
Importer	O
"	O
products	O
—	O
P2V	O
Assistant	O
allowed	O
users	O
to	O
convert	O
physical	O
machines	O
into	O
virtual	B-Architecture
machines	I-Architecture
,	O
and	O
Importer	O
allowed	O
the	O
import	O
of	O
virtual	B-Architecture
machines	I-Architecture
from	O
other	O
products	O
into	O
VMware	O
Workstation	O
.	O
</s>
<s>
vSphere	O
Client	O
(	O
formerly	O
VMware	B-Application
Infrastructure	I-Application
Client	O
)	O
,	O
enables	O
monitoring	O
and	O
management	O
of	O
a	O
single	O
instance	O
of	O
ESX	O
or	O
ESXi	B-Operating_System
server	O
.	O
</s>
<s>
After	O
ESX	O
4.1	O
,	O
vSphere	O
Client	O
was	O
no	O
longer	O
available	O
from	O
the	O
ESX/ESXi	O
server	O
but	O
must	O
be	O
downloaded	O
from	O
the	O
VMware	O
web	O
site	O
.	O
</s>
<s>
Cisco	O
offers	O
in	O
their	O
Cisco	B-Protocol
Nexus	I-Protocol
product-line	O
the	O
Nexus	O
1000v	O
,	O
an	O
advanced	O
version	O
of	O
the	O
standard	O
distributed	O
vSwitch	O
.	O
</s>
<s>
The	O
VSM	O
runs	O
as	O
a	O
virtual	B-Application
appliance	I-Application
within	O
the	O
ESX	O
cluster	O
or	O
on	O
dedicated	O
hardware	O
(	O
Nexus	O
1010	O
series	O
)	O
and	O
the	O
VEM	O
runs	O
as	O
a	O
module	O
on	O
each	O
host	O
and	O
replaces	O
a	O
standard	O
dvS	O
(	O
distributed	O
virtual	O
switch	O
)	O
from	O
VMware	O
.	O
</s>
<s>
Configuration	O
of	O
the	O
switch	O
is	O
done	O
on	O
the	O
VSM	O
using	O
the	O
standard	O
NX-OS	B-Operating_System
CLI	B-Application
.	O
</s>
<s>
It	O
offers	O
capabilities	O
to	O
create	O
standard	O
port-profiles	O
which	O
can	O
then	O
be	O
assigned	O
to	O
virtual	B-Architecture
machines	I-Architecture
using	O
vCenter	B-Application
.	O
</s>
<s>
The	O
Nexus1000v	O
is	O
developed	O
in	O
co-operation	O
between	O
Cisco	O
and	O
VMware	O
and	O
uses	O
the	O
API	B-Application
of	O
the	O
dvS	O
.	O
</s>
<s>
Because	O
VMware	B-Operating_System
ESX	I-Operating_System
is	O
a	O
leader	O
in	O
the	O
server-virtualization	O
market	O
,	O
software	O
and	O
hardware	O
vendors	O
offer	O
a	O
range	O
of	O
tools	O
to	O
integrate	O
their	O
products	O
or	O
services	O
with	O
ESX	O
.	O
</s>
<s>
Examples	O
are	O
the	O
products	O
from	O
Veeam	O
Software	O
with	O
backup	O
and	O
management	O
applications	O
and	O
a	O
plugin	O
to	O
monitor	O
and	O
manage	O
ESX	O
using	O
HP	B-Application
OpenView	I-Application
,	O
Quest	O
Software	O
with	O
a	O
range	O
of	O
management	O
and	O
backup-applications	O
and	O
most	O
major	O
backup-solution	O
providers	O
have	O
plugins	O
or	O
modules	O
for	O
ESX	O
.	O
</s>
<s>
VMware	O
has	O
added	O
a	O
Web	O
Client	O
since	O
v5	O
but	O
it	O
will	O
work	O
on	O
vCenter	B-Application
only	O
and	O
does	O
not	O
contain	O
all	O
features	O
.	O
</s>
<s>
vEMan	O
is	O
a	O
Linux	B-Operating_System
application	O
which	O
is	O
trying	O
to	O
fill	O
that	O
gap	O
.	O
</s>
<s>
As	O
of	O
September	O
2020	O
,	O
these	O
are	O
the	O
known	O
limitations	O
of	O
VMware	B-Operating_System
ESXi	I-Operating_System
7.0	O
U1	O
.	O
</s>
<s>
Some	O
maximums	O
in	O
ESXi	B-Operating_System
Server	O
7.0	O
may	O
influence	O
the	O
design	O
of	O
data	O
centers	O
:	O
</s>
<s>
Instructions	O
that	O
perform	O
this	O
extra	O
work	O
,	O
and	O
other	O
activities	O
that	O
require	O
virtualization	O
,	O
tend	O
to	O
lie	O
in	O
operating	B-General_Concept
system	I-General_Concept
calls	O
.	O
</s>
<s>
In	O
an	O
unmodified	O
operating	B-General_Concept
system	I-General_Concept
,	O
OS	O
calls	O
introduce	O
the	O
greatest	O
portion	O
of	O
virtualization	O
"	O
overhead	O
"	O
.	O
</s>
<s>
VMware	O
developed	O
the	O
Virtual	B-Architecture
Machine	I-Architecture
Interface	O
for	O
this	O
purpose	O
,	O
and	O
selected	O
operating	B-General_Concept
systems	I-General_Concept
support	O
this	O
.	O
</s>
<s>
A	O
comparison	O
between	O
full	B-Architecture
virtualization	I-Architecture
and	O
paravirtualization	O
for	O
the	O
ESX	B-Operating_System
Server	I-Operating_System
shows	O
that	O
in	O
some	O
cases	O
paravirtualization	O
is	O
much	O
faster	O
.	O
</s>
<s>
When	O
using	O
the	O
advanced	O
and	O
extended	O
network	O
capabilities	O
by	O
using	O
the	O
Cisco	B-Protocol
Nexus	I-Protocol
1000v	O
distributed	O
virtual	O
switch	O
the	O
following	O
network-related	O
limitations	O
apply	O
:	O
</s>
