Re: [ovirt-users] running vm when its configured memory is bigger than host memory

Currently, the virtual machine of given memory size S cannot be run on the host with less than S physical memory. We need to run several virtual machines (with unpredictable memory requirements) on the cluster consisting of several different hosts (with different amount of physical memory) in such the way that any virtual machine can be run on any host. Due to Ovirt limitation, virtual machines memory sizes has to be set to the MINIMUM of host physical memory sizes (in order to be able to run any virtual machine on any host). As far as I know, this rule has no connection to cluster's Memory optimization 'Max Memory Over Commitment' parameter. But we cannot predict memory needs of our virtual machines so we need to set the memory size of all of them to the MAXIMUM of host's physical memory sizes. Explanation: We are running several computational tasks (every one on single independent virtual machine). We have several (and different) host machines (see Figure 1). 1. At the beginning, every task consumes a decent amount of memory. 2. After a while, some task(s) allocate a huge amount of memory (Figure 2). At this moment, some of them cannot continue (due to unavailable memory on its current host) without migration to the host with higher memory available. 3. After migration (Figure 3), all tasks may continue. 4. Some tasks finally consumes a LOT of memory (Figure 4). The algorithm above cannot be realized, since every virtual machine (i.e. task) has predefined (and fixed when running) its memory size set to the MINIMUM of hosts physical memory sizes.