The "QCOW" in the extension stands for . This format was chosen by developers for several technical advantages:
A valid xbox-hdd.qcow2 file normally requires a copy of the files (protected by copyright). Distribution without owning the original hardware or software may violate copyright law. Emulator projects usually provide tools that let you create the file from an original Xbox’s hard drive or from a legal installation disc. xbox-hdd.qcow2
Emulator reports “No hard disk found” → Ensure file path is correct and image contains a master boot record with FATX partitions. The "QCOW" in the extension stands for