Home > Storage > PowerMax and VMAX > Storage Admin > Dell PowerMax and VMware vSphere Configuration Guide > vSphere Storage I/O Control
Performance issues can arise when many different virtual machine types share the same VMFS volume on a large SCSI disk that is presented to the ESXi hosts. Storage I/O Control was designed to help alleviate these issues. This technique of using a single large disk allows optimal use of the storage capacity. If the large SCSI disk hosting the VMFS cannot meet the I/O demands of the virtual machines despite using SIOC, this approach can cause performance issues.