openvz memory limitation ceiling?

[lastguru]

Hi,

I've done some searching on google and in this forum as well, but I can't seem to find any information as to why can't I set memory limit on my openvz guest more that the amount of physical memory on the host? Everywhere I go it is stated that physical+swap of the host counts, however whatever I say in Proxmox VE configuration, I only get up to the amount of physical memory of the host, and not a byte more...

Is there any way to overcome this limitation?

Thanks

 

[lp86]

I have to ask, why would you want to do something like that? If you over-allocate the memory and the container uses all of that available memory, it could crash the system.

 

[lastguru]

Why would it crash? I should swapout like any normal application, shouldn't it?

 

[lp86]

It will get very very slow, then just stop working, I have seen this happen even on a RAID array. A little swap is ok, but depending on it can only cause problems. OpenVZ is sensitive to disk IO from what I have seen.

Why do you want to allocate more physical memory then you physically have in the machine?

 

[lastguru]

Because OpenVZ does not calculate application memory usage correctly (for example, although OpenVZ thinks my VM uses all the memory allocated, there are huge amount of memory unused on the host)