You can reconfigure the amount of memory allocated to a virtual machine to enhance performance.

Minimum memory size is 4 MB for virtual machines that use BIOS firmware. Virtual machines that use EFI firmware require at least 96 MB of RAM or they cannot power on.

Maximum memory size for virtual machines that use BIOS firmware is 6128 GB. You must use EFI firmware for virtual machines with memory size greater than 6128 GB.

Maximum memory size for a virtual machine depends on the physical memory of the ESXi host and the virtual machine compatibility settings.

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 physical memory of the ESXi host 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 4 MB.

Table 1. Maximum Virtual Machine Memory
Introduced in Host Version Virtual Machine Compatibility Maximum Memory Size
ESXi 7.0 Update 1 ESXi 7.0 Update 1 and later 24560 GB
ESXi 7.0 ESXi 7.0 and later 6128 GB
ESXi 6.7 Update 2 ESXi 6.7 Update 2 and later 6128 GB
ESXi 6.7 ESXi 6.7 and later 6128 GB
ESXi 6.5 ESXi 6.5 and later 6128 GB
ESXi 6.0 ESXi 6.0 and later 4080 GB
ESXi 5.5 ESXi 5.5 and later 1011 GB
ESXi 5.1 ESXi 5.1 and later 1011 GB
ESXi 5.0 ESXi 5.0 and later 1011 GB
ESX/ESXi 4.x ESX/ESXi 4.0 and later 255 GB
ESX/ESXi 3.x ESX/ESXi 3.5 and later 65532 MB

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 65532 MB.

Prerequisites

Power off the virtual machine.

Verify that you have the Virtual machine.Configuration.Change Memory privilege on the virtual machine.

Procedure

  1. Click Virtual Machines in the VMware Host Client inventory.
  2. Right-click a virtual machine in the list and select Edit settings from the pop-up menu.
  3. On the Virtual Hardware tab, expand Memory.
  4. In the RAM text box, type the amount of RAM to assign to the virtual machine or select one of the suggested values from the drop-down menu.
  5. Select whether the memory is specified in MB, GB or TB.
  6. Click Save.