Installation guide

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VMware ESX Server Administration Guide
system performance, see Improving Slow Performance on Virtual Machines on
page 387.
• Its 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.
Note: You must specify a maximum memory size for a guest operating system,
or it will not boot. Also, you can only change a virtual machine’s maximum
memory size when it is powered off.
• Its 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 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.
Similarly, high shares are twice that of normal (or four times that of low).
The system automatically 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.
Setting Memory Minimum, Maximum, and Shares
You can set a memory minimum, memory maximum, and shares to manage memory
resources for your virtual machines. Memory minimums and maximums specify
absolutes, an absolute minimum or maximum memory usage by a virtual machine.
Shares, on the other hand, represent relative importance or priority. You set shares to
specify which virtual machines will get preferential treatment when ESX Server is
overcommitted.
For example, virtual machine A has a minimum memory size of 192MB, and a
maximum memory size of 256MB, while virtual machine B has a minimum memory
size of 256MB and a maximum memory size of 512MB.
You then decide to give virtual machine A high memory shares and virtual machine B
normal memory shares. By default, the setting for high is twice that of normal, or four