SCSI Read Capacity Command

The SCSI Read Capacity command is used to obtain data capacity information from a target device.

The CDB structure is:

The special control fields in the CDB have the following meaning:

• RelAdr - indicates that the LBA value is relative (only used with linked commands).
• PMI - partial medium indicator:
  • 0 - return value for the last LBA
  • 1 - return value for the last LBA after which a substantial delay in data transfer will be encountered (e.g. the current track or cylinder)

The target will return capacity data structured like this: