The control unit verifies the parameters and reserved fields in their order in
Table 4-7 on page 4-14, except it checks byte 0, bits 2 through 7 first. If the
control unit detects an exception condition in more than one parameter in Table 4-7
on page 4-14, it reports only the first exception.
Other restrictions are described in the following text.
Ending Status:
The control unit presents channel end status after it verifies the
parameters. If the operation uses cache, the track format information is known to
the Internal Disk, and the track and sector specified in the Locate Record command
is in cache, device end occurs with channel end. If the track format information is
not known to the Internal Disk or the track and sector are not in cache, the control
unit presents device end after it retrieves track format information from the logical
volume.
Locate Record Parameters
The Locate Record parameters are shown in Table 4-7.
Table
4-7. Locate Record Parameters
Byte
Parameter Name
0
Operation byte
1
Auxiliary byte
2
Reserved, must be zero.
3
Count
4–7
Seek address
8–12
Search argument
13
Sector number
14–15
Transfer length factor
Operation Byte – Byte 0
Byte 0 specifies the orientation to establish when track access is complete. It also
specifies the operations to perform in the Locate Record domain. The operation
byte is shown in Table 4-8.
Table
4-8. Operation Byte Definition
Byte 0 Bits
Orientation and Operation
0–1
Value Orientation Modifier
00 Count
area
01 Home
address
10 Data
area
11 Index
2–7
Value Operation Code
00 0000 Orient (00)
00 0001 Write Data (01)
00 0011 Format Write (03)
00 0110 Read Data (06)
00 1011 Write Track (0B)
00 1100 Read Tracks (0C)
01 0110 Read (16)
4-14
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 ...