Product : HPE, SimpliVity [HCI]/4.0.1 U1, 2600
Feature : Data Locality, General, Storage Support
Content Owner:  Herman Rutten
When a VM is created, it is optimally placed on the best 2 nodes available. When data is written, it is deduplicated and compressed on arrival, and then stored on the local node as well as a dedicated partner node. To keep the performance optimal through the VMs lifecycle, OmniStack automatically creates VMware vSphere DRS affinity rules and policies. This is called Intelligent Workload Optimization. VMware DRS is made aware of where the data of an individual VM is. In effect, the VM follows the data rather than having the data follow the VM, as this prevents heavy moves of data to the VM. When a HPE SimpliVity 2600 node is added to the federation, the DRS rules related to OmniStack are automatically re-evaluated.

Whether data locality is a good or a bad thing has turned into a philosophical debate. Its true that data locality can prevent a lot of network traffic between nodes, because the data is physically located at the same node where the VM resides. However, in dynamic environments where VMs move to different hosts on a frequent basis, data locality in most cases requires a lot of data to be copied between nodes in order to maintain the physical VM-data relationship. The SDS/HCI vendors today that choose not to use data locality, advocate that the additional network latency is negligible.