
Byte 1, Bit 7:
When set to ‘1’, specifies that the last data transfer command in the
Locate Record Extended domain will be a Read Count command. The Read Count
command is a suffix to the Locate Record Extended domain. The record is
included in the count of records processed as specified by the count parameter.
The Read Count command suffix is valid for a Locate Record Extended command
specifying Write Data (01), or Read (16) operations, or the Extended Operations of
Write Any (09), or Read Any (0A). If this bit is set on for any other code, the
command is rejected with unit check status. The sense data contains command
reject with format 0, message 4.
Not Used – Byte 2
Byte 2 must contain zeros. If byte 2 does not contain zeros, the Locate Record
Extended command is rejected with unit check status. The sense data contains
command reject with format 0, message 4.
Count – Byte 3
Byte 3 contains the count which determines the domain (region of influence) of the
Locate Record Extended command. Usually, the count parameter specifies the
number of records or tracks to be operated on within the Locate Record domain.
Specific use of the count parameter depends on the operation code in byte 0.
“Locate Record Extended Operations” on page 4-34 describes each operation
code.
The count must not be zero. If the Read Count command suffix (byte 1, bit 7) is
set to ‘1’, the count must be greater than 1. If the count does not satisfy these
requirements, the command is rejected with unit check status. The sense data
contains command reject with format 0, message 4.
Note:
The user must ensure that the count is accurate. If the number of write
CCWs is less than specified in the count field, a unit check indicating
incomplete domain may be presented to the current or next I/O operation to
this logical volume.
Seek Address – Bytes 4–7
Bytes 4 through 7 specify a seek address (cylinder and head, CCHH). The value in
bytes 4 through 7 must be a valid track address for the logical volume. If the seek
address is not valid, the command is rejected with unit check status. The sense
data contains command reject with format 0, message 4.
If the extended operation code is Read Any (0A) or Write Any (09), and the seek
address does not specify a primary track, the command is rejected with unit check
status. The sense data contains command reject with format 0, message 4. See
Appendix A, "Device Characteristics" on page A-1 for valid track address ranges.
If the seek address is not in the extent defined in the preceding Define Extent
command, the command is terminated with unit check status. The sense data
includes File Protected.
Chapter 4. Command Descriptions
4-31
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