Question about VM memory
- Thread starter Fritz
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In VirtualBox, I believe it is allocated at VM start and locked. KVM has memory ballooning, but the guest OS needs to support it.
Easy enough to test, allocate enough RAM to a couple VMs so that it can't load the second if you have the first running. Turn off swap "swapoff" should do it, and launch them.
Easy enough to test, allocate enough RAM to a couple VMs so that it can't load the second if you have the first running. Turn off swap "swapoff" should do it, and launch them.
Thanks. Just read a thread on another forum about this and the question never answered, just stupid advice like "Give your VM enough memory and you won't have to worry about swappyness" and other equally stupid answers. And the basic question was never answered "How you you disable swapping in Virtualbox?".
But it did just occur to me that maybe if I disable swapping within the VM that this might do it??
And thanks T_Minus, your answer answered my question.
But it did just occur to me that maybe if I disable swapping within the VM that this might do it??
And thanks T_Minus, your answer answered my question.
Yes sir, after more research I do believe you are correct.
ACK!!! after rereading the above i realized this is not correct. The host OS, being Ubuntu-MATE would have nothing to do with the VM's. I believe you meant it was done within the VM's. If not, please clarify.
Actually overcomitting memory on virtual machines is in many cases a good idea, It is not recommended to disable swap as you will just get "less" resources to play around with.
The reason overcommiting memory is good, is that you let the operating system decide what memory is "hot" and what is "cold". Though in many cases it can also be dangerous, especially on Linux. FreeBSD is much better, but its virtualization software Bhyve is still young. I have no idea about VMWare, but as a top tier enterprise product, I guess it performs excellent and is stable with overcommited memory.
The reason overcommiting memory is good, is that you let the operating system decide what memory is "hot" and what is "cold". Though in many cases it can also be dangerous, especially on Linux. FreeBSD is much better, but its virtualization software Bhyve is still young. I have no idea about VMWare, but as a top tier enterprise product, I guess it performs excellent and is stable with overcommited memory.
Couple things to keep in mind here though is that he's not running vmware and he's only disabling swap to test how virtualbox allocates memory. I don't see any issues with this, maybe I missed something though?
By default, Virtualbox only allocates 4MB of memory to a new virtual machine. Can't see this being small amount being of much use in the real world. It's nice to know how it handles memory allocation. With 2 Win 7 VM's running with each having 8GB allocated to them, the second one to start was sluggish. But Ubuntu didn't seem to be affected at all. Don't quite understand why, maybe it has priority over the VM's?