With VMware vSphere IT administrators can consolidate many servers onto fewer physical hosts. However in such scenarios, random spikes in resource requirements of the applications running in virtual machines may lead to uneven system resource utilization. A basic approach to solve this problem is to estimate the demands of the VMs upfront and distribute them across the hosts. However, this sort of manual load balancing doesn't offer a complete solution. A dynamic VM load balancing approach is required. VMware Distributed Resource Scheduler is the only solution that offers dynamic VM load balancing today.
I recently did few experiments with a vSphere cluster and DRS. I noticed significant improvement in application performance with DRS. I wrote a blog documenting my experiments and results. You can find the blog on VROOM. Feel free to post your questions, comments on the experiments in the blog, any interesting experiences with DRS or DRS in general. I hope the information discussed here will be useful for lot of you folks out there.