2.4. Changing the Dom0 Memory Size

When you install Oracle VM Server, the installer sets a default memory size for Dom0. The algorithm used is:

dom0_mem = 502 + int(physical_mem * 0.0205)

Example sizes are set out in table Table 2.1.

Table 2.1. Default Dom0 Memory Size

Physical Memory

Dom0 Memory

2 GB

543 MB

4 GB

585 MB

8 GB

669 MB

16 GB

837 MB

32 GB

1173 MB

64 GB

1845 MB

128 GB

3188 MB

256 GB

5875 MB

512 GB

11249 MB

1024 GB

21997 MB

2048 GB

43493 MB

You may encounter performance issues if the dom0 memory size is not set appropriately for your needs on the Oracle VM Server. For example, you may encounter performance issues when running more than 10 virtual machines on an Oracle VM Server.

To change the Dom0 memory allocation, edit the /boot/grub/grub.conf file on the Oracle VM Server and change the dom0_mem parameter, for example, to change the memory allocation to 1024 MB, edit the file to be:

kernel /xen.gz console=com1,vga com1=38400,8n1 dom0_mem=1024M