Data processing: structural design – modeling – simulation – and em – Emulation – Of peripheral device
Reexamination Certificate
1999-07-28
2003-06-03
Ingberg, Todd (Department: 2123)
Data processing: structural design, modeling, simulation, and em
Emulation
Of peripheral device
C703S023000, C703S024000, C360S048000, C710S068000, C710S074000, C711S202000, C711S206000, C711S111000
Reexamination Certificate
active
06574589
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an input/output control system. More particularly, the present invention relates to an input/output control system suitable for an application in which accesses to an internal auxiliary storage device such as a disk unit embedded in an information processing apparatus are made by another information processing apparatus.
A general-purpose information processing system or the like normally employs a disk unit as an element of an auxiliary storage sub-system. Thus, the information processing system needs to carry out operations to input and output data from and to the disk unit.
FIG. 4
is a block diagram showing a typical configuration of an information processing system employing a disk unit based on a prior art.
FIG. 5
is an explanatory diagram showing an example of a series of channel commands and
FIG. 6
is an explanatory diagram showing a typical flow of commands and data between an information processing apparatus and a disc sub-system. An input/output control system based on the prior art is explained by referring to
FIGS. 4
to
6
. In
FIG. 4
, reference numerals
20
and
21
denote an information processing apparatus and an input/output (I/O) channel. Reference numeral
22
denotes a central processing unit (CPU) and reference numeral
25
denotes a disc-subsystem. Reference numerals
26
and
27
denote a disk unit and a cache respectively. Reference numeral
28
denotes a disc control unit.
The information processing system based on the prior art as shown in
FIG. 4
comprises the information processing apparatus
20
and the disc-subsystem
25
. The information processing apparatus
20
includes a plurality of I/O channels
21
for controlling exchanges of information between the information processing apparatus
20
and external equipment such as the disc-subsystem
25
. The I/O channels
21
are connected to the disc sub-system
25
which comprises a plurality of disk units
26
each having a fixed-length format (FBA format) and the disc control unit
28
including the cache
27
. The disk units
26
operate under control executed by the disc control unit
28
.
The I/O channel
21
issues a necessary command to the disc control unit
28
in order to make an access to data stored in the disk unit
26
. The disc control unit
28
controls the disk units
26
in accordance with the command received from the I/O channel
21
. This command is prepared by an operating system (OS) executed by the CPU
22
employed in the information processing apparatus
20
as a channel command word (CCW) for controlling data and the disk units
26
.
Viewing the disk units
26
controlled by the disc control unit
28
as a storage unit for storing data with a variable-length format or a CKD (Count Key Data) format provided by a CKD architecture, an I/O channel
21
issues a request to input or output data with a CKD format to the disc control unit
28
. The disc control unit
28
carries out command emulation including conversion of the CKD format into an FBA format.
It should be noted that a method to emulate a disk unit with the CKD format by using a disk unit with the FBA format is disclosed for example in Japanese Patent Laid-open No. Hei 6-150557.
The following description explains typical CCW commands issued by the information processing apparatus
20
to the disc sub-system
25
to exchange data with the CKD format as well as a flow of data and the CCW commands.
Normally, the CPU
22
issues a series of CCWs like ones shown in FIG.
5
. The series of commands shown in
FIG. 5
includes a SEEK command
30
for selecting a track by specifying a cylinder number and a head number. The series of commands also includes a SET SECTOR command
31
for positioning the head on a target sector indicated by a sector number specified in the command. Every track of a disk unit
26
is logically divided into sectors each having shape resembling a flap and an equal space.
The series of commands also includes a SEARCH ID command
32
for positioning the head on a target record. The target record can be confirmed by comparison of a record ID specified in the SEARCH ID command
32
with the record ID of a count read out from the disk unit
26
. The series of commands also includes a TIC command
33
. The TIC command
33
is a command for confirming that the target record has been found by the SEARCH ID command
32
. The SEARCH ID command
32
and the TIC command
33
are executed repeatedly till the record desired by the SEARCH ID command
32
is found. The series of commands also includes a READ/WRITE command
34
for reading out or writing data from or into a record found by the series of preceding commands.
The following is a description of a flow of CCW commands output by the information processing apparatus
20
to the disc sub-system
25
following activation of an operation of the I/O function by the series of CCW commands prepared by the OS running on the information processing apparatus
20
with reference to FIG.
6
.
The OS executed by the CPU
22
employed in the information processing apparatus
20
prepares the series of CCW commands for controlling data and a disk unit and stores the CCW commands in a main storage device. Then, the OS requests an I/O channel
21
to activate an operation of the I/O function for outputting the series of CCW commands to a disk unit
26
. The operation of the disk unit
26
is then controlled by the disc control unit
28
in accordance with the series of the CCW commands. In this way, the CCW commands are sequentially transmitted by the CPU
22
to the disc control unit
28
by way of the I/O channel
21
. To put it in detail, first of all, the I/O channel
21
reads out the SEEK command
30
from the main storage device and transmits the command to the disc control unit
28
. As described earlier, the SEEK command
30
is placed at the head of the series of CCW commands stored in the main storage device. The I/O channel
21
then waits for an emulation of the SEEK command
30
to be completed by the disc control unit
28
. The emulation includes a conversion of the SEEK command
30
from a CKD format into an FBA format. As the emulation is finished, the disc control unit
28
informs the I/O channel
21
of the completion.
Notified by the disc control unit
28
of the completion of the emulation, the I/O channel
21
transmits the next SET SECTOR command
31
to the disc control unit
28
on accordance with the same procedure as the preceding SEEK command
30
. As described earlier, the SET SECTOR command
31
is a second command in the series of CCW commands. The I/O channel
21
then waits for the disc control unit
28
to transmit a notice reporting completion of processing of the SET SECTOR command
31
. Receiving the notice, the I/O channel
21
repeats the same processing to transmit the SEARCH ID command
32
to the disc control unit
28
and waits for a notice of completion. The disc control unit
28
reports a notice of completion along with a result indicating a found record to the I/O channel
21
.
Receiving the notice of completion from the disc control unit
28
, the I/O channel
21
fetches the TIC command
33
from the main storage device. The TIC command
33
is executed by the I/O channel
21
to form a judgment as to whether or not the found record is a record desired by the SEARCH ID command
32
. If the outcome of the judgment indicates that the found record is not the desired record, the I/O channel
21
retransmits the SEARCH ID command
32
to the disc control unit
28
. This processing is carried out repeatedly till the found record matches the desired record. As the found record in the notice of completion matches the desired record specified in the SEARCH ID command
32
, the I/O channel
21
fetches the READ/WRITE command
34
following the TIC command
33
from the main storage device and transmits the READ/WRITE command
34
to the disc control unit
28
.
The I/O channel
21
waits for an emulation of the READ/WRITE command
34
including a conversion from a
Ingberg Todd
Mattingly Stanger & Malur, P.C.
Thomson W
LandOfFree
Information processing system for sharing internal auxiliary... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Information processing system for sharing internal auxiliary..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Information processing system for sharing internal auxiliary... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3115318