The geometry returned must be the same for both the IOCM_GET_MEDIA_GEOMETRY and the IOCM_GET_DEVICE_GEOMETRY commands. For both commands, only the TotalSectors and the BytesPerSector fields should be set. The TotalSectors field should be equal to the last addressable logical block address on the media + 1. This value should correspond to the value returned in the SCSI-2 Read Capacity command + 1, which is the starting address of the lead out area. The BytesPerSector field should be set to 2048. TheNumHeads, TotalCylinders and SectorsPerTrack fields should be set to 0.

If there is no media present in the drive, the driver should return IOERR_UNIT_NOT_READY.