Stage four of the EDRM is collection . Be sure to recognize that the are two basic forms of collection - physical collection and logical collection. Physical collection is the imaging of an actual hard drive - including its unallocated space. Logical collection involves collecting from the virtual constructs presented to a user by an operating system - for example in Windows one may have the C drive logical volume and the D drive logical volume - each actually part of one drive. A volume level logical collection may consist of a single volume from multiple hard drives - perhaps a Redundant Array of Independent Disks (RAID). A distinction may be made between logical volume collection and folder level logical collections.