
Write Data
Hex Code
Data Address
Count
05
The main storage location of the data.
The number of bytes to write.
Description:
The Write Data command updates the data area of an existing
record. Processing depends on whether this command is inside of or outside a
Locate Record or Locate Record Extended domain.
In the Domain of a Locate Record
Orientation is to a count area (as the result of the preceding Locate Record or
Locate Record Extended command). The control unit then writes the following data
area.
The control unit gets data from the channel and writes it into the data area of the
record. If the Locate Record operation is Write Track (0B), the subsystem assumes
a transfer length factor of 8 bytes for the R0 data field (see “Write Track – ‘0B’
Operation Code” on page 4-23). If the Locate Record operation is Write Data (01),
the amount of data is defined in the Locate Record or Locate Record Extended
transfer length factor parameter (or the Define Extent block size parameter if no
transfer length factor was specified). If the channel provides fewer than (DL) bytes,
binary zeros fill the remaining bytes of the data area.
If the transfer length factor (or blocksize) value is not equal to the count area data
length value of the record, the control unit action depends upon whether the Define
Extent specified CKD conversion mode.
If CKD Conversion mode (byte 1 bit 2 is ‘0’) is not specified, the record is not
updated. The operation is terminated with unit check status. The sense data
will be 24-byte Compatibility format and includes Invalid Track Format.
If CKD Conversion mode (byte 1, bit 2 is ‘1’) is specified in the Define Extent,
the control unit does the following:
– If the data length is zero, no data transfer is attempted. The operation is
rejected with status that include unit exception.
– If the actual length of the data field is not zero, then the operation is
rejected with unit check status. The sense data is ECKD 32-Byte format
and includes Invalid Track Format, Exception Class 0, and program action
code of X
'
0F
'
.
Chaining and Restrictions:
Unit check status with the sense data containing
command reject with format 0, message 2 occurs if this command is not in a
Locate Record or Locate Record Extended domain specifying:
A Write Data (01) operation that requires only one write operation (either a
count of 1, or with read count suffix, a count of 2).
A Write Track (0B) operation.
Ending Status
Channel end status is presented when data transferred from the
channel is completed. Device end status is presented when the Write operation is
completed at the logical volume. When the command completes, the control unit is
oriented to the data area of the record just updated.
Chapter 4. Command Descriptions
4-97
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