Changing the Oracle VM Dom0 Memory Size
When you install Oracle VM Server 3.0, the installer sets a default memory size for Dom0. The algorithm used is:
dom0_mem = 502 + int(physical_mem * 0.0205)
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.
The following table show example sizes based pn physical memory
| 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 |
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