
‘100’ – Sequential Prestage
: In the Internal Disk Subsystem, this setting is
treated the same as Normal Cache Replacement.
‘101’ – Record Access
: Indicates that there is little locality of reference of the
data accessed by this channel program.
Byte 1, Bit 6 – Reserved, must be zero:
If this bit is set to ‘1’, the command is
terminated with unit check status. The sense data contains command reject with
format 0, message 4.
Byte 1, Bit 7 – Reserved, ignored:
This bit is reserved and ignored. It should be
set to ‘0’, but will not cause an error if set to ‘1’.
Blocksize – Bytes 2 and 3
Bytes 2 and 3 specify the blocksize in bytes as an unsigned 16-bit binary value.
This value specifies the maximum number of bytes for a single record in the
channel program. A zero value is valid and is the same as specifying the
maximum record length supported by the device. The maximum record length is 8
plus maximum size of R1.
When a following Locate Record or Locate Record Extended command contains an
update write type operation without a transfer length factor, the blocksize value
must be the
exact
data length (or sum of key and data lengths if the key area is to
be updated) of each record in the Locate Record or Locate Record Extended
domain. See “Write Data – ‘01’ Operation Code” on page 4-20.
The proper blocksize value depends on what areas of the record are to be sent.
The value is one of the following:
The data length (DL)
The key length (KL) plus DL
The sum of DL and KL plus 8 (for the count area).
If the blocksize exceeds the logical volume’s track capacity (maximum R1 length
plus eight), 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 the maximum record lengths.
Not Used – Bytes 4, 5 and 6
Bytes 4, 5 and 6 must contain zeros. If these bytes do not contain zeros, the
command is rejected with unit check status. The sense data contains command
reject with format 0, message 4.
Global Attributes Extended – Byte 7
Only the content of Bit 5, Byte 7 is used by the Internal Disk Subsystem. Bits 0-4
and bits 6-7 of Byte 7 are reserved. In the Internal Disk Subsystem, they are
ignored and should be set to zeros.
Bit 5 indicates Regular Record Zero. If Bit 5 is set to one, the Internal Disk
Subsystem accepts permission to format write Record Zero with a standard R0 that
has the following content:
The CCHH is equal to the currently addressed cylinder and track.
The R value is zero.
The Key Length is zero.
The Data Length is 8.
4-12
Internal Disk Subsystem Reference Guide
Содержание Multiprise 3000
Страница 1: ...S 390 Multiprise 3000 Enterprise Server R IBM Internal Disk Subsystem Reference Guide SA22 1025 00 ...
Страница 2: ......
Страница 3: ...S 390 IBM Internal Disk Subsystem Reference Guide SA22 1025 00 ...
Страница 32: ...2 12 Internal Disk Subsystem Reference Guide ...
Страница 38: ...3 6 Internal Disk Subsystem Reference Guide ...
Страница 182: ...4 144 Internal Disk Subsystem Reference Guide ...
Страница 198: ...5 16 Internal Disk Subsystem Reference Guide ...
Страница 214: ...6 16 Internal Disk Subsystem Reference Guide ...
Страница 234: ...A 10 Internal Disk Subsystem Reference Guide ...
Страница 238: ...B 4 Internal Disk Subsystem Reference Guide ...
Страница 243: ...4 lease the Code or any copy of it Appendix C Warranties C 5 ...
Страница 244: ...C 6 Internal Disk Subsystem Reference Guide ...
Страница 248: ...D 4 Internal Disk Subsystem Reference Guide ...
Страница 254: ...X 6 Internal Disk Subsystem Reference Guide ...
Страница 263: ......
Страница 264: ...IBM Printed in the United States of America on recycled paper containing 10 recovered post consumer fiber SA22 1 25 ...