Dell Storage with Microsoft Storage Spaces Best Practices Guide

Dell recommends that fixed VHDX files with default parameters are used for Converged solutions involving Hyper-V VMs, as this results in optimal performance. If you decide to use dynamically expanding VHDXs, ensure that you have available storage for the VD to expand. If expansion happens and there is no available storage the VMs can suddenly pause and create outages. Also, file fragmentation can occur as the VHDX file increases in size over time, which can lead to overall reduced speed when compared to a VHDX that has been fully allocated at creation.