What is the difference between DRS and SDRS?

VMWare Distributed Resource Scheduler and VMWare Storage Distributed Resource Scheduler are two similar and related technologies that offer benefits for administrating virtualized hardware systems.

Essentially, VMWare Storage DSR is a subset or component of VMWare DSR that relates specifically to storage solutions in a virtualized environment.

VMWare DSR is a scheduling tool for virtualization. In hardware virtualization, a hypervisor links various virtual machines, each of which receives resources from a given pool. Individual virtual machines receive virtual memory and CPU according to the tasks that they need to complete, and the allocations that administrators have set for them. A scheduler helps to provide resources in real time, by either active or passive allocations of virtualization resources like virtual memory and virtual CPU.

By contrast, VMWare Storage DSR is a component that looks specifically at storage needs and storage activity, in order to do provisioning for virtual machines. VMWare Storage DSR or "SDSR" is also a branded offering by VMWare, but unlike VMWare DSR, its focus is on how data storage works in the virtualized environment. VMWare resources state that VMWare Storage DSR "monitors datastore capacity and I/O" and that SDSR can help 'place’ virtual machines in a system or do load-balancing based on storage metrics such as I/O and space capacity.