6.5.1

The memory resource settings for a virtual machine determine how much of the host's memory is
allocated to the virtual machine. The virtual hardware memory size determines how much memory is
available to applications that run in the virtual machine. A virtual machine cannot benefit from more
memory resources than its configured virtual hardware memory size. ESXi hosts limit the memory
resource use to the maximum amount useful for the virtual machine, so that you can accept the default of
Unlimited memory resources.
Change the Memory Configuration
You can reconfigure the amount of memory allocated to a virtual machine to enhance performance.
Minimum memory size is 4MB for virtual machines that use BIOS firmware. Virtual machines that use EFI
firmware require at least 96MB of RAM or they cannot power on.
Maximum memory size for a virtual machine depends on the host's physical memory and the virtual
machine's compatibility setting.
If the virtual machine memory is greater than the host memory size, swapping occurs, which can have a
severe effect on virtual machine performance. The maximum for best performance represents the
threshold above which the host’s physical memory is insufficient to run the virtual machine at full speed.
This value fluctuates as conditions on the host change, for example, as virtual machines are powered on
or off.
The memory size must be a multiple of 4MB.
Table 5‑3. Maximum Virtual Machine Memory
Introduced in Host Version Virtual Machine Compatibility Maximum Memory Size
ESXi 6.5 ESXi 6.5 and later 6128GB
ESXi 6.0 ESXi 6.0 and later 4080GB
ESXi 5.5 ESXi 5.5 and later 1011GB
ESXi 5.1 ESXi 5.1 and later 1011GB
ESXi 5.0 ESXi 5.0 and later 1011GB
ESX/ESXi 4.x ESX/ESXi 4.0 and later 255GB
ESX/ESXi 3.x ESX/ESXi 3.5 and later 65532MB
The ESXi host version indicates when support began for the increased memory size. For example, the
memory size of a virtual machine with ESX/ESXi 3.5 and later compatibility running on ESXi 5.0 is
restricted to 65,532MB.
Prerequisites
Verify that you have the Virtual machine.Configuration.Memory privilege on the virtual machine.
Procedure
1 Right-click a virtual machine in the inventory and select Edit Settings.
2 On the Virtual Hardware tab, expand Memory.
vSphere Virtual Machine Administration
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