Specifications

Administration Guide
346 VMware, Inc.
Allocating Memory Resources
Three!parameters!control!the!allocation!of!memory!resources!to!each!virtual!machine:
! Minimum!size!–!min
The!minimum!size!is!a!guaranteed!lower!bound!on!the!amount!of!memory!that!is!
allocated!to!the!virtual!machine,!even!when!memory!is!overcommitted.!The!
system!uses!an!admission!control!policy!to!enforce!this!guarantee.!You!cannot!
power!on!a!new!virtual!machine!if!there!isn’t!
sufficient!memory!to!reserve!its!
minimum!size.
Set!a!virtual!machine’s!minimum!for!the!minimal!acceptable!performance!and!
above!the!threshold!where!the!guest!operating!system!begins!swapping!heavily.!
Use!the!performance!monitoring!tool!of!the!guest!operating!system!to!see!if!you!
are!swapping.!For!information!on!improving!guest!operating!
system!performance,!
see!“Improving!Slow!Performance!on!Virtual!Machines”!on!page 330.
! Maximum!size!–!max
The!maximum!size!is!the!amount!of!memory!configured!for!use!by!the!guest!
operating!system!running!in!the!virtual!machine.!This!maximum!size!must!be!
specified!in!the!configuration!file!for!the!virtual!machine.!By!default,!virtual!
machines!operate!at!their!maximum!allocation,!unless!memory!is!
overcommitted.
! Share!allocation
Memory!shares!entitle!a!virtual!machine!to!a!fraction!of!physical!memory.!For!
example,!a!virtual!machine!that!has!twice!as!many!shares!as!another!is!generally!
entitled!to!consume!twice!as!much!memory,!subject!to!their!respective!minimum!
and!maximum!constraints,!provided!they!are!both!actively!using!the!
memory!they!
have!been!allocated.
You!can!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.!
Similarly,!high!shares!are!twice!that!of!normal!(or!four!times!that!of!low).
The!system!allocates!
an!amount!of!memory!to!each!virtual!machine!somewhere!
between!its!minimum!and!maximum!sizes!based!on!its!shares!and!an!estimate!of!its!
recent!working!set!size.
N
OTE Specify!a!maximum!memory!size!for!a!guest!operating!system,!or!it!will!not!boot.!Also,!
you!can!change!a!virtual!machine’s!maximum!memory!size!only!when!it!is!powered!off.!