1.6 Changing the Memory Size of the Management Domain

When you install Oracle VM Server, the installer sets a default memory size for dom0. The algorithm used is:

(768 + 0.0205 * Physical memory (MB)) round to 8

You can use this calculation to determine memory allocation for the Oracle VM Server installation. However, you should not make the memory allocation for dom0 smaller than the calculated value. You can encounter performance issues if the dom0 memory size is not set appropriately for your needs on the Oracle VM Server.

Example sizes are set out in table Table 1.1.

Table 1.1 Default Dom0 Memory Size

Physical Memory

Dom0 Memory

2 GB

816 MB

4 GB

856 MB

8 GB

936 MB

16 GB

1104 MB

32 GB

1440 MB

64 GB

2112 MB

128 GB

3456 MB

256 GB

6144 MB

512 GB

11520 MB

1024 GB

22264 MB

2048 GB

32768 MB


32768 MB is the maximum allowed memory for dom0.

To change the dom0 memory allocation, edit your grub configuration on the Oracle VM Server to adjust the value for the dom0_mem parameter. If you are using UEFI boot, the grub configuration file is located at /boot/efi/EFI/redhat/grub.cfg, otherwise the grub configuration file is located at /boot/grub2/grub.cfg. Edit the line starting with multiboot2 /xen.mb.efi and append the required boot parameters. For example, to change the memory allocation to 1440 MB, edit the file to contain:

multiboot2 /xen.mb.efi dom0_mem=max:1440M placeholder ${xen_rm_opts}