JPH0830399A - Data transmission system - Google Patents

Abstract

PURPOSE:To provide a data transmission system for shortening access time on the host side especially at the time of reading at a disk array device for handling large capacity data. CONSTITUTION:This system is provided with plural magnetic disk devices 15, host devices 11a and 11b for performing the read access of data to the magnetic disk devices 15, disk switch 13 provided between the magnetic disk devices 15 and the host devices 11a and 11b for switching data simultaneously read from the plural magnetic disk devices 15 at high speed and transferring them to the plural host devices 11a and 11b, and disk switching controller 14 for controlling the switching of read data from the disk to the host to the disk switch 13 while receiving instructions from the host devices 11a and 11b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system capable of reading a large amount of data in a multi-host configuration.

[0002]

2. Description of the Related Art In recent years, the information handled by a computer has changed from multimedia data to multimedia as it includes voice data and moving image data. As a result, even in the case of a magnetic disk device which has been generally used as a storage device up to now, a system having a capacity of several hundred megabytes was sufficient, but an extremely large capacity storage capacity for handling image data. A device is required, and multiple disks of several gigabyte class are arranged in parallel and read at the same time for high-speed access. Furthermore, in order to make such image data accessible by a number of terminals of a few hundreds to a thousand, a video-on-demand system is also being realized in which the number of hosts is increased and corresponding.

An example of the above-mentioned conventional disk array system will be described below with reference to the drawings.

FIG. 7 is a block diagram of a disk array system in a conventional embodiment.

In FIG. 7, 51a and 51b are two host devices in a multi-host configuration, 52 is the entire disk array device to which the host devices 51a and 51b are connected, and 53a and 53b are the host devices 51a and 51b. Reference numeral 51b is a disk array control device for controlling magnetic disk access in the entire disk array device, 54 is a plurality of magnetic disk devices in the entire disk array device, and 54a and 54b are a plurality of magnetic disk devices. An individual magnetic disk device 54n is an nth magnetic disk device (n is a natural number) of the plurality of magnetic disk devices.

The operation of the disk array system configured as described above will be described below.

In the example of FIG. 7, two host devices 51a and 51b are used in the multi-host configuration, but as the system scale increases, additional host devices will be added. The host devices 51a and 51b are connected to the disk array device 52, and control is performed through the disk array control devices 53a and 53b in order to access the internal magnetic disks. In the plurality of magnetic disk devices 54, n disks from magnetic disk devices 54a to 54n are connected by a common bus. Disk array controller 53a, 5
3b receives the data read requests from the host devices 51a and 51b, respectively, the magnetic disk device 54a.
To 54n, the corresponding data stored in a distributed manner are simultaneously accessed to perform high-speed reading. The disk array control devices 53a and 53b select and fetch data output to the common bus, store it in a buffer memory or the like, and store necessary data in the respective host devices 51a and 51b.
Transfer control to.

[0008]

However, in the above-mentioned conventional configuration, since the interface between a plurality of magnetic disks and the host is of a fixed bus system, the data amount is increased by multiplexing the disks. In addition to the above, if a host expansion in a multi-host configuration occurs,
There was a problem that access time was delayed due to the soaring bus usage rate. There are also problems that the arbitration process between hosts becomes complicated and that a large capacity buffer memory is required.

In view of the above conventional problems, it is an object of the present invention to provide a data transmission system which can further shorten the access time of a host to a disk as compared with the conventional system.

[0010]

According to the present invention of claim 1, there are provided a plurality of memory means for storing data, a plurality of host devices each individually connected to the plurality of memory means, and the memory means. And a plurality of connection switching means for individually switching the connection between the host device and the host device, and a switching control device for controlling the switching operation of the connection switching means.

According to the second aspect of the present invention, predetermined data that is frequently read by the host device is stored in one memory means, and a plurality of types of such data exist. If so, the data are data transmission systems stored in separate said memory means.

According to a third aspect of the present invention, the memory means comprises:
Data having a plurality of disk devices and frequently read by a predetermined one predetermined host device is stored in one memory means, and the memory means and the predetermined host device A table indicating the relationship with the above is stored in the switching control means, and when there is a read request from the plurality of host devices for the frequently read data, the switching control device refers to the table. , A data transmission system for controlling the switching operation of the connection switching means so as to give priority to the predetermined host device.

According to a fourth aspect of the present invention, there is provided a data transmission system in which the memory means stores audio data and / or moving image data, and a video-on-demand terminal is connected to the host device.

[0014]

According to the present invention, a plurality of memory means store data, a plurality of host devices are individually connected to the plurality of memory means, and a plurality of connection switching means are provided for the memory means and the host device. And the connection between them are individually switched, and the switching control device controls the switching operation of the connection switching means.

With the above configuration, for example, the bus neck in the fixed bus system is eliminated, and high-speed access to the magnetic disk device is made possible by only switching the switches without performing complicated bus arbitration processing. If data can be continuously read from the magnetic disk device at high speed, the buffer memory can be reduced as much as possible to perform data transfer. Furthermore, for example, by considering the method of storing data in the magnetic disk device and the switch control, it is possible to easily realize system multiplexing for each host in a multi-host configuration.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram of a disk array system as an embodiment of a data transmission system of the present invention, and the configuration of this embodiment will be described with reference to the drawing.

In FIG. 1, 11a and 11b are two host devices in the multi-host configuration, and 12 is the entire disk array device to which the host devices 11a and 11b are connected. Reference numeral 15 is a plurality of magnetic disk devices in the entire disk array device 12, 15a and 15b are individual magnetic disk devices of the plurality of magnetic disk devices, and 15n.
Is the n-th magnetic disk device (n is a natural number)
Magnetic disk device. The memory means of the present invention is the magnetic disk device 15a, 15b, ..., 15n.
Corresponding to. A disk switch 13 is provided between the plurality of magnetic disk devices 15 and the host devices 11a and 11b, and switches data read simultaneously from the plurality of magnetic disk devices 15 at high speed to distribute the data to the plurality of host devices. The disk switch 13 includes the connection switching means of the present invention. 14 is the host device 11
It is a disk switching control device which receives commands from a and 11b and controls the disk switch 13 to switch read data from the magnetic disk device 15 to the host devices 11a and 11b. The switching control device of the present invention corresponds to the disk switching control device 14.

The operation of the disk array system configured as described above will be described below with reference to FIGS. 1 and 2.

In FIG. 1, two host devices 11a and 11b are used in the multi-host configuration as in the conventional example, but as the system scale increases, additional host devices will be added. The host devices 11a, 11b, ... Are connected to the disk array device 12, but the disk switch 13 is provided between them and the internal magnetic disk devices 11a to 11n, as described above.

When the host device 11a reads data, a data read request is issued to the disk switching control device 1
Send to 4. The disk switching control device 14 switches the data bus to the disk switch 13 so that the data is sent to the host device a, and the magnetic disk device 15
Control is performed so that corresponding data stored in a distributed manner from a to 15n are simultaneously accessed and read.

FIG. 2 is a schematic diagram showing a switch portion in the disk switch 13 in this embodiment.

In FIG. 2, 21 is a disk switch 1
3 is a switch unit, 22a to 22c are host buses when three host devices 11a to 11c are connected in a multi-host configuration, and 23a to 23e are magnetic disk devices.
It shows a disk bus when 5 units (a = 15e) (n = 5) are connected.

When transferring the requested data from the host device 11a, all the disk buses 23a to 23e are connected to the host bus 22a as shown in FIG. Similarly, when transferring requested data from the host devices 11b and 11c, the disk buses 23a to 23e are connected to the host buses 22b and 22c, respectively. At that time, disk bus 2
Switching of 3a to 23e is performed all at once for the same host bus. The priority of these connections is determined by the order in which the disk switching control device 14 receives the data read request.

A case where such a configuration is applied to a video-on-demand system will be described with reference to FIG.

FIG. 3 is a schematic diagram showing how data is transferred by periodically switching the disk switch, and the horizontal axis represents the time axis.

That is, in the video-on-demand system, a terminal is connected to each host device, and in order to read data for all of the terminals, magnetic data is sequentially transferred to each host device within a unit time (time slot). Data is read from the disk device (see FIG. 3). Therefore, the data transfer can be completed by periodically switching the disk switch without using the complicated bus arbitration function.

Since data is read from the magnetic disk device every unit time, the host memory can be used as long as the buffer memory corresponds to the amount of data for a unit time without providing a large capacity buffer memory. Data can be transferred to the device.

(Second Embodiment) Next, another embodiment of the data transmission system of the present invention will be described with reference to the drawings.

FIG. 4 is a block diagram of the disk array system in this embodiment. In this embodiment, the multi-host configuration is the same as that of the first embodiment, but the difference from FIG. 1 is that a plurality of magnetic disk devices are added in the column direction to form a two-dimensional array. On the other hand, the main difference between the control methods is the disk switch switching control method.

In FIG. 4, 31a and 31b are two host devices in the multi-host configuration, and 32 is the entire disk array device to which the host devices 31a and 31b are connected. Reference numeral 35a1 denotes a plurality of magnetic disk devices that form a two-dimensional array in the entire disk array device 32.
˜35a3 is a of the plurality of magnetic disk devices 35
Individual magnetic disk devices in the row, 35b1 to 35b3 are individual magnetic disk devices in the b row among the plurality of magnetic disk devices 35, and 35n1 to 35n3 are the nth line (n in the plurality of magnetic disk devices 35). Is a natural number) of each magnetic disk device. The plurality of disk devices of the present invention correspond to the magnetic disk devices 35n1 to 35n3. Reference numeral 33 is provided between the plurality of magnetic disk devices 35 and the host devices 31a and 31b, and switches data read simultaneously from each row of the plurality of magnetic disk devices 35 at high speed and distributes the data to the plurality of host devices 31a and 31b. It is a disk switch. Reference numeral 34 is a disk switching control device that receives commands from the host devices 31a and 31b and controls the disk switch 33 to switch read data from the magnetic disk device 35 to the host devices 31a and 31b.

The operation of the disk array system configured as described above will be described below with reference to FIGS. 4 and 5.

In FIG. 4, when the host device 31a reads data, it sends a data read request to the disk switching control device 34. In the case of this embodiment, the read data is different from that of the first embodiment, and the magnetic disk device 35 of the a-th row
It is assumed that three a1 to 35a3 are continuously stored. Three units are arranged in order to improve the transfer rate between rows. As a result, the disk switching control device 34 causes the disk switch 33
The data bus is switched so that the data is sent to a, and the corresponding data stored in the magnetic disk devices 35a1 to 35a3 on the a-th row is accessed and read.

FIG. 5 is a schematic diagram showing a switch unit in the disk switch 33 in this embodiment.

In FIG. 5, similarly to the first embodiment, 41 is a switch unit in the disk switch 33, and 42a to 42c are host buses when three host devices 31a to 31c are connected in a multi-host configuration. Reference numerals 43a to 43e represent disk buses when the magnetic disk devices are connected to a to e for 5 rows (n = 5). If the requested data from the host device 31a is stored in the magnetic disk device of the a-th row, when transferring data, the disk bus 43a is connected to the host bus 42a as shown in the figure. Similarly, if the requested data of the host devices 31b and 31c are stored in the magnetic disk devices of the b-th row and the d-th row, respectively, when transferring the data, the disk bus 43b is connected to the host bus 42b and the disk bus 43b is transferred to the disk bus as shown in the figure. 43d is connected to the host bus 42c. In FIG. 5, the disk bus 43c is connected to the host bus 42a and the disk bus 43e is connected to the host bus 42b, but data transfer is not performed. As a result, the read data from the magnetic disk device can be switched at high speed line by line in the magnetic disk device and transferred to the host device side. Therefore, files frequently accessed by each host device can be stored in each line of the magnetic disk device. If the data is classified and stored in, the disk switch 33 hardly switches, the bus utilization efficiency on the host side is improved, and system multiplexing in host units can be easily implemented. In addition, the access speed can be increased by controlling the switching of the disk switch differently from the first embodiment.

Next, another example different from the case of the first embodiment regarding the method of determining the priority order regarding connection will be described.

The difference from the first embodiment is that the disk switching control device 14 is not necessarily determined only by the order in which the data read requests are received, but is also determined in consideration of the above-mentioned access frequency.

That is, the disk switching control device 34
Is provided with a table (not shown) showing the relationship between one predetermined host device and a magnetic disk device corresponding to one row of the disk array that is frequently accessed by the host device.

That is, for example, the host device 31a frequently accesses the magnetic disk devices 35a1 to 35a3, and the host device 31b frequently accesses the table to the magnetic disk devices 35b1 to 35b.
These relationships are recorded in a state of 3, ...

Therefore, for example, when data read requests to read predetermined data from the magnetic disk devices 35a1 to 35a3 are issued from the host devices 31a and 31b at substantially the same time, the disk switching control device 34.
Performs the following control. It is not strictly necessary that the host devices 31a and 31b be slightly behind each other.

That is, the disk switching control device 34
Are the host devices 31a and 3 that have been accepted within a predetermined time.
The table is referred to based on the content of each data read request from 1b. Then, the disk switching control device 34 uses the contents described in the table to determine the host device 31a.
It is determined that the data read request from the device should be prioritized, and the operation of the disk switch 33 is controlled so that the disk bus 43a is connected to the host bus 42a.

On the other hand, a case where the above configuration is applied to, for example, a video-on-demand system will be described.

In the video-on-demand system, as described above, files having high access frequency for each host device are stored together in one row of the disk array, so that when there are n host devices, At the optimum time, the access time is n times faster. FIG. 6 shows this state.

That is, in FIG. 6, the disk data is
It shows how optimal multiplexing can be realized for access from each host device if distributed optimally.
The horizontal axis represents the time axis as in FIG.

Further, in the case where the plurality of magnetic disk devices are arranged in row units in this way, one magnetic disk having a larger storage capacity is used instead of the plurality of magnetic disk devices provided in the row units. Compared to the configuration using the device, a general-purpose type magnetic disk device can be used, and the like, which is advantageous in terms of total cost when realizing the system.

The above embodiment is effective for a disk array system for performing high-speed and large-capacity data transfer required for a continuous video data supply server or the like. It is possible to eliminate the system bus neck and realize efficient access in a multi-host configuration.

In the above embodiment, the case where the magnetic disk device is used as the disk device has been described, but the present invention is not limited to this, and for example, an optical disk device may be used.

Further, in the above embodiment, the case where the host device reads data from the memory means has been described, but the present invention is not limited to this. For example, the data is written in the memory means. The same effect can be obtained.

[0049]

As is apparent from the above description, the present invention has an advantage that the access time of the host device with respect to the memory means can be further shortened as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a disk array system according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a switch unit in a disk switch according to this embodiment.

FIG. 3 is a schematic diagram showing how data is transferred in this embodiment.

FIG. 4 is a configuration diagram of a disk array system in another embodiment according to the present invention.

FIG. 5 is a schematic diagram showing a switch unit in a disk switch according to another embodiment of the present invention.

FIG. 6 is a schematic diagram showing optimum multiplexing of access from each host device in another embodiment according to the present invention.

FIG. 7 is a block diagram of a disk array system in a conventional example.

[Explanation of symbols]

11a, 11b Host device 12 Disk array device 13 Disk switch 14 Disk switching control device 15 Multiple magnetic disk devices 15a, 15b Magnetic disk device 15n nth magnetic disk device 21 Switch part in disk switch 22a-22c Host device 11a To 11c Host buses 23a to 23e Magnetic disk devices 15a to 15e
Disk bus 31a, 31b Host device 32 Disk array device 33 Disk switch 34 Disk switching control device 35 Plural magnetic disk devices 35a1 to 35a3 Magnetic disk device 35a1 to 35b3 ab Line magnetic disk device 35n1 to 35n3 Magnetic disk device in n-th row 41 Switch unit in disk switch 42a to 42c Host bus to host devices 31a to 31c 43a to 43e Disk bus of magnetic disk device in a-th to e-th rows 51a, 51b Host device 52 disk Array device 53a, 53b Disk array control device 54 Plural magnetic disk devices 54a, 54b Magnetic disk device 54n nth magnetic disk device

Claims (4)

[Claims] 1. A plurality of memory means for storing data, a plurality of host devices respectively connected to the plurality of memory means, and a connection between the memory means and the host device individually. A data transmission system, comprising: a plurality of connection switching means for switching between the connection switching means and a switching control device for controlling a switching operation of the connection switching means. 2. Predetermined data that is frequently read by the host device is stored in one memory means, and if there are multiple types of such data, those data are stored. Are stored in separate memory means.
The described data transmission system. 3. The memory means has a plurality of disk devices, and data which is frequently read by a predetermined one predetermined host device is stored in one of the memory means. A table showing the relationship between the memory means and the predetermined host device is stored in the switching control means, and the switching control is performed when there are read requests from the plurality of host devices for the frequently read data. 3. The data transmission system according to claim 1, wherein the device controls the switching operation of the connection switching means so as to give priority to the predetermined host device with reference to the table. 4. The memory means stores audio data and / or moving picture data, and a video-on-demand terminal is connected to the host device. The described data transmission system.