Specifications

Administration Guide
332 VMware, Inc.
entitled!to!consume!twice!as!much!CPU!time,!subject!to!their!respective!minimum!
and!maximum!percentages.
You!may!specify!shares!by!specifying!a!numerical!value,!or!specifying! high,!
normal,!or!low.!By!default,!the!setting!for!normal!shares!is!twice!that!of!low.!The!
setting!for!high!shares!is!
twice!that!of!normal!(or!four!times!that!of!low).
You!can!specify!a!minimum!percentage,!a!maximum!percentage,!CPU!shares,! or!a!
combination!of!these.!The!system!automatically!allocates!CPU!time!to!each!virtual!
machine!somewhere!between!its!minimum!and!maximum!percentages,!refined!by!the!
number!of!shares.!
Admission Control Policy
ESX!Server!uses!an!admission!control!policy.!While!CPU!reservations!are!used!for!
admission!control,!actual!CPU!time!allocations!vary!dynamically!and!unused!
reservations!are!not!wasted.
Specifying Minimum and Maximum CPU Percentages
Starting!with!ESX!Server!2.0,!you!can!specify!a!minimum!and!maximum!percentage!of!
CPU!for!each!virtual!machine.!The!minimum!percentage!represents!an!absolute,!fixed!
lower!limit!while!the!maximum!percentage!represents!an!absolute,!fixed!upper!limit.!A!
virtual!machine!will!use!at!least!as!much!CPU!time!as!specified
!by!the!minimum!
percentage!and!never!use!more!CPU!time!than!the!specified!maximum!percentage.
For!a!single!virtual!CPU!virtual!machine,!the!percentage!ranges!from!0%!to!100%.!For!
a!dual‐virtual!CPU!machine,!the!percentage!ranges!from!0%!to!200%.
For!example,!if!one!of!your!virtual!machines!is!
running!an!important!application,!you!
can!specify!a!higher!minimum!percentage!for!this!virtual!machine,!compared!to!the!
other!virtual!machines!on!your!ESX!Server.!
For!example,!you!plan!to!run!20!virtual!machines!on!your!ESX!Server!machine,!but!have!
currently!deployed!only!five!virtual!machines.!These!five!virtual!machines
!would!
utilize!any!extra!CPU!time!that!is!available!on!the!ESX!Server!machine.!However,!after!
N
OTE If!ESX!Server!is!unable!to!guarantee!a!virtual!machine’s!specified!minimum!percentage,!
it!will!not!allow!you!to!power!on!that!virtual!machine.
NOTE Set!a!virtual!machine’s!minimum!for!the!minimal!acceptable!performance.
NOTE You!can!set!CPU!percentages!for!some,!or!all!of!your!virtual!machines.!Alternately,!you!
can!set!only!minimum,!or!only!maximum!CPU!percentages.!You!do!not!need!to!set!both.