Memory used to host Oracle VM server, whats left for the guests?

Question

I've built my first test Oracle VM server on a small celeron powered machine with 1.5GB RAM. I created a PV OEL5 guest and initially gave it 512MB RAM. Now if I increase this to 1024MB and try to start the system I get the error...
failed:<OVSException: no server selected to run vm('/OVS/running_pool/50_OELr5r3') memory=1024> StackTrace: File "/opt/ovs-agent-2.2/OVSSiteVM.py", line 77, in start_vm raise e
A little research implies this error is because not enough memory is available to run the OS. So how much from the 1.5GB of RAM is actually available for guests? I would be surprised to learn that 512MB is used JUST for the host environment. Doing a cat /proc/meminfo gives me the following;
*[root@ovm ~]# cat /proc/meminfo*
MemTotal:       545968 kB
MemFree:        335464 kB
Buffers:         75120 kB
Cached:          58392 kB
SwapCached:          0 kB
Active:         143920 kB
Inactive:        22356 kB
So 533MB available to the host OS... This leaves just under a gig For the guests, but I can't find where the max is detailed. I can't find anything in the docs which detail how much resources the base Oracle VM server uses and if it's possible to tune this.

Answer 1

Simon Thorpe wrote:
So 533MB available to the host OS... This leaves just under a gig For the guests, but I can't find where the max is detailed. I can't find anything in the docs which detail how much resources the base Oracle VM server uses and if it's possible to tune this.Check /boot/grub/menu.lst -- the memory for Dom0 is set on the kernel boot line. You can lower this, but don't go too low. I usually recommend about 10% of total memory be dedicated to Dom0 up to a max of 3.5GB, so on a 1.5GB box, you could probably drop to 150MB or so. Keep in mind that Dom0 is a 32-bit kernel, so you don't want to go over 3.5GB without good reason.