Resource pools are special containers used to allocate resources to a group of VMs. Previously, we have seen that the use of shares, reservation, and limit parameters allows the assignment of resources to a single VM. Unfortunately, this cannot be considered the most efficient approach for resource management, especially in large environments where the number of VMs can be high.
The use of resource pools improves resource management and can be useful to compartmentalize the resources available in a cluster, adding scalability for the control of resources for groups of VMs. Resource pools can be created in an ESXi host or in a DRS-enabled cluster.
To create a resource pool in a cluster (the procedure is similar also for the single ESXi host), proceed as follows:
- Right-click the cluster and select the New Resource Pool option.
- Specify a name for the resource pool giving a meaningful name useful to better identify the resource scope.
- Specify how CPU and RAM resources should be allocated then click OK. When the resource pool has been created, you can start adding VMs to it. Share values set as High, Normal, or Low specify share values in a 4:2:1 ratio:
You may ask how do resource pools work?. To explain how they work, take a look at the following example. Two resource pools have been created that correspond to two different departments—RP-DEV, configured with CPU shares and memory set to High, and RP-SALES, with both set to Normal. The host can provide 6 GHz of CPU and 3 GB of memory that must be shared between the RP-DEV and RP-SALES departments:
Until RP-DEV doesn't use all resources, RP-SALES can use available resources. In the case of resource contention, RP-DEV will get 4 GHz of CPU and 2 GB of memory while RP-SALES will get 2 GHz and 1 GB.
Using resource pools, resources assigned to a group of VMs can be adjusted from a single point with no need to edit every single VM.