Everyone wants to tweak their virtualization environment for optimum performance. This means modifying default settings to better suit your particular infrastructure. Rick Vanover recently shared a little known setting for VMware vSphere that gives a slight boost to disk access. The setting is called disk.schednumreqoutstanding and is set to 32 by default. If you have more than 1 VM on a LUN, setting this value higher (the max is 256) can improve performance because this setting specifies a limit to the maximum number of outstanding disk requests to a specific LUN.