VMware DRS (Distributed Resource Scheduler) is a feature of ESX that balances
computing workloads with available resources in a virtualized
environment.
When you enable a cluster for DRS, VirtualCenter continuously monitors the distribution
of CPU and memory resources for all hosts and virtual machines in the cluster. DRS compares these metrics to what resource utilization ideally should be given the attributes of the resource pools and
virtual machines in the cluster, and the current load.
Note that DRS is only available in ESX Enterprise or above.
When DRS is enabled in a cluster, ESX then will automagically vmotion guest VMs to other hosts in your cluster in an attempt to ballance out the load evenly across the cluster. However, sometimes this behavior is not always desired. For exmaple if you have a large VM that you want to stay pinned to a particular host.
In order to override the default DRS cluster settings for a vm, you need to do the following.
- Right Click on your cluster and then click on “edit settings“
- Under DRS, click on “Virtual Machine Options“
- Locate the particular VM and the drop down box under “Automation Level“
- Change “Default (Fully Automated)” to “Manual“