Electrical computers and digital data processing systems: input/ – Input/output data processing – Input/output access regulation
Reexamination Certificate
2002-07-31
2004-11-02
Gaffin, Jeffrey (Department: 2182)
Electrical computers and digital data processing systems: input/
Input/output data processing
Input/output access regulation
C710S001000, C711S114000
Reexamination Certificate
active
06813655
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a disk control apparatus employed for a disk system apparatus that enables data to be stored in plural magnetic disk units.
2. Description of Related Art
Many efforts have been made to bring input/output performance of a disk subsystem (referred to as subsystem, hereinafter) which uses magnetic disks as recording media, close to that of a computer equipped with main memory, which uses a semiconductor storage unit as recording media, because the performance of the former is as low as about {fraction (1/1000)} to {fraction (1/10000)} of that of the latter.
Employment of a disk control apparatus that enables data to be stored in plural magnetic disk units is one of the methods for improving the input/output performance of the subsystem.
For example, the conventional well-known disk control apparatus shown in
FIG. 6
includes one or more disk control clusters (referred to as the cluster, hereinafter)
101
in addition to plural channel interface units
10
used to transfer data between a host computer
60
and the cluster
101
, plural disk interface units
20
used to transfer data between a magnetic disk unit
70
and the cluster
101
, a cache memory unit
30
used to store data to be read/written from/in the magnetic disk unit
70
, and a resource management unit
90
used to store information related to the cluster
101
(for example, information related to the controlling of the data transfer between each of the channel interface units
10
/disk interface units
20
and the cache memory unit
30
, and management information of the data to be stored in the magnetic disk unit
70
).
The disk capacity and the number of host channels connectable to one cluster
101
are limited. When data must be stored over the limited disk capacity and/or when host computers
60
in a number larger than that of host channels that can be connected to one cluster have to be connected, therefore, the disk control apparatus is provided with plural clusters
101
.
A data path network
400
is used for the connection between each of the plurality of channel interface units
10
/disk interface units
20
and the cache memory unit
30
over the plurality of clusters
101
.
Similarly, a resource management network
500
is used for the connection between each of the plurality of channel interface units
10
/disk interface units
20
and the resource management unit
90
over the plurality of clusters
101
.
Consequently, the resource management unit
90
and the cache memory unit
30
can be accessed from every channel interface unit
10
and every disk interface unit
20
.
Each of the channel interface units
10
includes an interface with a host computer
60
and a microprocessor (not shown) for controlling the input/output to/from the host computer
60
.
Each of the disk interface units
20
includes an interface with a magnetic disk unit
70
and a microprocessor (not shown) for controlling the input/output to/from the magnetic disk unit
70
.
The disk interface unit
20
is also used to execute the RAID functions.
The data path network
400
is configured so as to include one or more switches
80
.
When data is transferred from a channel interface unit
10
/disk interface unit
20
to the cache memory unit
30
through the data path network
400
, packets are used for the data transfer. Each packet includes a destination address added to the initial position of the data written therein.
The transfer of those packets to the target cache memory unit
30
through the data path network
400
is controlled by the microprocessor provided in each channel interface unit
10
or disk interface unit
20
.
Each switch
80
, as shown in
FIG. 7
, includes plural path interfaces
41
connected to the data path network
400
, plural packet buffers
43
and plural address latches
44
, as well as a selector
48
.
In each path interface
41
, a header analyzer
42
is included. The header analyzer
42
is used to take out address information from each packet, thereby the analyzed and extracted packet address is fetched into the corresponding address latch
44
.
On the other hand, received packets are stored in a packet buffer
43
through the corresponding path interface
41
.
Each address latch
44
generates a selector control signal
47
according to the destination address of each packet and the selector
48
selects a path to the destination address of each packet stored in the packet buffer
43
.
In this way, the path change for each packet in the conventional switch
80
is decided fixedly by the packet address.
This is why a path of packets through the data network
400
must be preset under the control of the microprocessor built in the subject channel interface unit
10
/disk interface unit
20
.
Especially, when a packet is to pass plural switches
80
provided in the data path network
400
, the path change information for those switches
80
is added to the packet in prior to the transfer.
The latest business environment, which is rapidly changing day by day, demands a high scalability disk control apparatus that allows a user to expand his/her business facilities step by step while suppressing his/her initial investment cost.
Such disk control apparatus needs to have high scalability that can cope with various scales of company's facilities, ranging from small to very large scale, to meet the users' needs. This demands that the apparatus needs to have flexibility to cope with the number of channels for connections to host computers, as well as with data capacity of each of its magnetic disk units.
The conventional techniques shown in
FIGS. 6 through 8
have been difficult to flexibly change the configuration of the channel interface unit/disk interface unit for the connections to the host computers in correspondence with the users' needs, since a microprogram presets the path on the way in the data bus network
400
between each of the channel interface units
10
/disk interface units
20
and the cache memory unit
30
.
In addition, the packet traffic in the data path network
400
has a partiality. Any of the conventional techniques described above, which fixes the path of packets cannot realize path optimization while the path for packet transfer can be optimized to increase the total number of packets to be transferred in the data path network
400
.
This is why the performance of the disk control apparatus has been degraded significantly due to the band limitation of the data path network
400
while the number of the channel interface units
10
/disk interface units
20
increases.
Furthermore, when the disk control apparatus is configured by plural clusters
101
, the microprocessor in each channel interface unit
10
or disk interface unit
20
is required to control every switch
80
in the path for path changes. Along with an increase in the number of the clusters
101
, the connections to those clusters
101
come to be complicated, the processing load of the microprocessors increases, thereby the data transfer to/from the host computer
60
and the magnetic disk unit
70
is often disturbed. This is why the performance of the disk control apparatus has been degraded.
Under such circumstances, it is an object of the present invention to provide a disk control apparatus configured so as to realize scalability and enabled to change the configuration to a smaller/larger one with the same enhanced architecture of a high reliability, as well as to solve the problems of the conventional techniques.
More concretely, it is an object of the present invention to provide a disk control apparatus to be expanded flexibly in correspondence with users' requirements and enabled to adjust the connection state therein as needed, and furthermore to provide a disk control apparatus whose performance is prevented from degradation more effectively even in a configuration having a very large cluster scale.
SUMMARY OF THE INVENTION
In achieving the objects in one preferred aspect, we utilize a disk contr
Fujimoto Kazuhisa
Hosoya Mutsumi
A. Marquez, Esq. Juan Carlos
Fisher Esq. Stanley P.
Gaffin Jeffrey
Kim Harold
Reed Smith LLP
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