rafaelrwrc wrote:
Hi Gabrie,
I know this topic is old, but that is what I was looking for a long time and your answers helped me a lot. There is only one thing I need to know to be satisfied and more slight! When u said: "With limits you should also be careful since these immediately impact the performance because they will swap to disk all memory above the limit. A common mistake is that admins set the limit equal to the assigned memory. There is no need for that and it will actually impact DRS performance.", I just wanna know "who" will swap to disk?! Host or VM? Since I had set a limit, I understood that ESXi wouldn't swap to disk whom would do this would be VM. Wouldn't it?
In the last example:
2- When the VM starts using more than 756MB, all memory above 756MB will be used from the Swap disk, which is very slow compared to physical RAM.
In this case, what I understood was: ESXi has physical memory enough, but because of set limit, ESXi won't give more memory to VM, however for VM 1024 GB was set, so VM starts to swap to disk.
I don't know if I made myself understood. Really thanks!
Swap will be done by the host and it will be the memory of the VM that will be swapped. It is always host memory since we're talking about physical RAM of the ESXi host and by setting a limit you will limit the VMs usage of that physical RAM.
Dont get confused by swapping that is done inside of the guest, this is purely a guest OS thing.
And on number 2: yes you're correct. The guest OS sees 1024MB, a limit is set to 756MB, all memory that is in use by the VM that is above the 756MB will not be given from physical RAM, so the host will swap this VM memory to disk.