User Manual

SCSI Commands Reference Manual, Rev. J 45
www.seagate.com General Concepts
2.3 Parameter Rounding
Certain parameters sent to a SCSI target port with various commands contain a range of values. Targets may choose to
implement only selected values from this range. When the target receives a value that it does not support, it either rejects the
command (CHECK CONDITION status with Illegal Request Sense key) or it rounds the value received to a supported value. The
target shall reject unsupported values unless rounding is permitted in the description of the parameter.
Rounding of parameter values, when permitted (Rounding is enabled by MODE SELECT command, page code 00h, byte 2, bit 2)
shall be performed as follows:
a SCSI target port that receives a parameter value that is not an exact supported value shall adjust the value to one that it
supports and shall return CHECK CONDITION status with a sense key of Recovered Error. The additional sense code shall be set to
Rounded Parameter. The initiator is responsible to issue an appropriate command to learn what value the target has selected.
Implementor’s Note: Generally, the target should adjust maximum-value fields down to the next lower supported value than
the one specified by the initiator. Minimum-value fields should be rounded up to the next higher supported value than the one
specified by the initiator. In some cases, the type of rounding (up or down) is explicitly specified in the description of the
parameter.