Another new feature of vSphere 4.1 is the DRS-Fault Tolerance integration. vSphere 4.1 allows DRS not only to perform initial placement of the Fault Tolerance (FT) virtual machines, but also migrate the primary and secondary virtual machine during DRS load balancing operations. In vSphere 4.0 DRS is disabled on the FT primary and secondary virtual [...]

vSphere 4.1 introduces DRS VM-Host Affinity rules and offer two types of rules, mandatory (must run on /must not run on) and preferential (should run on /should nor run on). When creating mandatory rules, all ESX hosts not contained in the specified ESX Host DRS Group are marked as “incompatible” hosts and DRS\VMotion tasks will [...]

In vSphere 4.1 a new network Load Based Teaming (LBT) algorithm is available on the distributed virtual switch dvPort groups. The option “Route based on physical NIC load” takes the virtual machine network I/O load into account and tries to avoid congestion by dynamically reassigning and balancing the virtual switch port to physical NIC mappings. [...]

vSphere 4.1 introduces a lot of new features and enhancements of the existing features, one of the hidden gems I believe is the DPM enable and disable scheduled tasks. The DPM “Change cluster power settings” schedule task allows the administrator to enable or disable DPM via an automated task. If the admin selects the option [...]