Figure 3-2. Memory Ballooning in the Guest Operating System
1
2
3
memory
memory
memory
swap space
swap space
NOTE You must configure the guest operating system with sufficient swap space. Some guest operating
systems have additional limitations.
If necessary, you can limit the amount of memory vmmemctl reclaims by setting the sched.mem.maxmemctl
parameter for a specific virtual machine. This option specifies the maximum amount of memory that can be
reclaimed from a virtual machine in megabytes (MB). See “Set Advanced Virtual Machine Attributes,” on
page 99.
Using Swap Files
You can specify the location of your swap file, reserve swap space when memory is overcommitted, and delete
a swap file.
ESX/ESXi hosts use swapping to forcibly reclaim memory from a virtual machine when the vmmemctl driver is
not available or is not responsive.
n
It was never installed.
n
It is explicitly disabled.
n
It is not running (for example, while the guest operating system is booting).
n
It is temporarily unable to reclaim memory quickly enough to satisfy current system demands.
n
It is functioning properly, but maximum balloon size is reached.
Standard demand-paging techniques swap pages back in when the virtual machine needs them.
NOTE For optimum performance, ESX/ESXi hosts use the ballooning approach (implemented by the vmmemctl
driver) whenever possible. Swapping is a reliable mechanism of last resort that a host uses only when necessary
to reclaim memory.
vSphere Resource Management Guide
30 VMware, Inc.
