To :  X3T9.2 SCSI Committee                            X3T9.2/89-16r1
From : Pete Bramhall, Hewlett-Packard                  Date : 1/10/89

Subject : Selection of ECC and other data reliability enhancers from the set
          available on a particular device

Issue :  Some sequential access devices and medium formats, particularly
         helical scan, provide a number of methods of increasing the
         reliability of recorded data, for example by writing multiple
         layers of ECC or writing multiple copies of the data. They also
         allow a host to select which method(s) shall be used. At present
         no facilities are defined for an initiator to make this selection
         or discover the current selection.

Proposal :  Redefine bytes 9 and 10 of Mode Select/Sense Read-Write Error
            Recovery Parameters Page (01h)

Byte 9 :    ECC Generation Control
            Value 0 :   indicates device's default algorithms 
            Values 1-255 : indicate an alternate ECC algorithm set which is 
                           specific to the device and medium format in use.

Byte 10 :   Repetitions
            Values 0-255 indicate the number of times the recorded data is
            repeated on the medium. A value of zero indicates no repeats,
            i.e. the data is written once only.