virtualbox.org

Ramshankar wrote:Remember there is a bit of overhead besides just the allocated RAM for a VM process. It's not like if you assign 3.5 GB RAM to a guest that the VM process is hard limited to *exactly* that amount. I can't tell you what exactly the overhead is and can be slightly different between headless and GUI VMs too.

Many of them says Oracle 12c RAC can be installed with 2 VMs each of 4GB , i am not sure what is their physical memory
In my case i have 12G physical memory and 8G allocated to VMs and on host there is nothing runing, not even IE or chorme pages opened
Task manager clearly shows availabel 3+G , my installation fails to low memory on host by 2nd VMs crashing ..

What is your memory usage (in MB/GB and %) at these precises times :
- in an empty desktop, where nothing is running
- after the 1st VM has started and is fully loaded and all services are running
- when the 2nd VM crash
- after you've shutdown both VMs

sivakumarnvn wrote:Why VBox is crashing when already available memory 4g it shows in Task manager ?

I already told you -- what is shown in the Task Manager is irrelevant. When VirtualBox asks for the memory, it doesn't get it, that's the only thing that matters.

In some cases, it's even possible that there is enough free memory, but it's not sufficiently contiguous or not the right kind of memory or whatever. Did you try running the same VMs on a host system with 16GB RAM?

sivakumarnvn wrote:

Ramshankar wrote:Remember there is a bit of overhead besides just the allocated RAM for a VM process. It's not like if you assign 3.5 GB RAM to a guest that the VM process is hard limited to *exactly* that amount. I can't tell you what exactly the overhead is and can be slightly different between headless and GUI VMs too.

Many of them says Oracle 12c RAC can be installed with 2 VMs each of 4GB , i am not sure what is their physical memory

The overhead I mentioned is for the VM process on the host, and not anything to do with Oracle 12C RAC.