JP3525421B2 - Data providing apparatus and method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data server providing apparatus and method suitable for use in, for example, a video server system for providing a video on demand service.

[0002]

2. Description of the Related Art FIG. 9 shows an example of the configuration of a conventional video server system. The video server 101 performs editing, processing, etc. on video (video data), voice (audio data), and other data (for example, text data) supplied from an information provider, and becomes multimedia data. Forming a multimedia library,
The data is recorded in a predetermined recording medium (storage) 102. That is, for example, the video and the accompanying audio are associated with each other,
In addition, other data can be associated if necessary,
It is recorded on the recording medium 102.

On the other hand, a user operates the terminal 104, and the video server 101 is operated via a network 103 such as a CATV (cable television) network or a telephone network.
When the desired data (video) is requested to the recording medium 1, the video server 101 sends the requested data to the recording medium 1.
02, and sends it to the terminal 104 via the network 103.

As described above, the data (video) desired by the user is provided to the user.

[0005]

By the way, in the conventional video server system, a magnetic tape is used as the recording medium 102. This is because magnetic tape is cheap,
This is because a large amount of data can be recorded and the system can be configured at low cost.

However, when a magnetic tape is used as the recording medium 102, there is a problem of lacking real-time property. That is, in this case, for example, to meet the immediacy required for the video-on-demand service,
There is a problem that it is difficult to perform special reproduction (for example, rewind, fast forward, still reproduction, frame forward reproduction, slow reproduction, etc.) that is possible with (video tape recorder).

Therefore, for example, with a tape changer,
There is a system (so-called library management system) that sets a recording medium 102, which is a magnetic tape on which data (video) according to a user's request is recorded, to a reproducing device and reproduces it. There was a problem that it was difficult to deal with users (provide services).

Further, as long as a tape-shaped recording medium such as a magnetic tape is used as the recording medium 102, it is difficult to randomly access the data.

Therefore, as the recording medium 102, a disk-shaped recording medium which can be accessed at high speed and has high throughput (for example, a hard disk (magnetic disk))
Alternatively, there is a system using a magneto-optical disk (hereinafter appropriately referred to as MO disk), a hard disk array including a plurality of hard disks (hard disk devices), or an MO disk array including a plurality of MO disks (MO disk devices).

For example, as a hard disk array, RAID (Redundant Arrays of Independent Dielectric), which is a high-performance and highly reliable data to which error correction technology is applied, is used.
sks) has been realized, and by applying such a hard disk array (hard disk) or MO disk array (MO disk) to a video server system, data can be randomly accessed. . Furthermore, according to the user's request,
Data can be provided in real time.

By the way, when recording, for example, video data of a movie of 2 hours on the recording medium 102 as data,
Even if the image data can be compressed to, for example, 6 Mbps by image compression processing based on so-called MPEG2, the amount of video data for 2 hours is 5.4 G (giga) bytes (= 6 Mbps × 60 seconds × 60 minutes ×). 2 hours ÷ 8 bits). Therefore, when performing a video-on-demand service, for example, if 1000 movies (movies for 2 hours each) are prepared, the recording medium 102 has a capacity of at least 5.4 T (tera) bytes. Is required. That is, the recording medium 102 is required to have a huge recording capacity.

Since the magnetic disk and the MO disk are more expensive than the magnetic tape, the magnetic disk and the MO disk (hereinafter, both of them will be appropriately used) as the recording medium 102 for recording the enormous amount of data as described above. Called a disk)
However, when using a magnetic disk array or an MO disk array (hereinafter, both are appropriately referred to as a disk array), there is a problem that the cost of the entire system increases.

In order to meet various demands from users, it is necessary to use a disk array having a switching capacity of, for example, several thousands to tens of thousands, and the system is
There has been a problem of further increasing the cost.

The present invention has been made in view of such circumstances, and it is possible to provide data in response to a user's request in real time and at low cost.

[0015]

A data providing apparatus according to the present invention comprises a large-capacity first recording means in which data is recorded, a plurality of second recording means which can be accessed at high speed, and a plurality of first recording means. A plurality of read / write control means for reading / writing data from / to each of the two recording means, and a transmitting means for transmitting the data read from the corresponding second recording means by the read / write control means to the terminal via the network. When,
The data for which an access request is issued from the terminal is a plurality of second data.
Determination control means for determining whether or not the data is recorded in any of the recording means, and controlling the data transmission based on the result of the determination , and a storage means for storing the frequency of access requests from the terminal to the data. By the judgment control means,
It is determined that the data is recorded in any of the plurality of second recording means, and the frequency of the access request stored in the storage means is set to the first predetermined value corresponding to the data. If it is less than or equal to the threshold value, the data is deleted from any of the second recording means which records the data,
Corresponding to the first predetermined threshold and the data in advance
And a deletion means for resetting the set second predetermined threshold value , wherein the judgment control means is configured to record a plurality of second record data.
A second record, if recorded by any of the means
Send data to the network from
Control is performed so that the data is stored in a plurality of second recording means.
It was recorded in some way and stored in the storage means.
When the frequency of access requests is equal to or higher than the second predetermined threshold value.
Data is recorded among the plurality of second recording means.
Copy to any second recording means not recorded
Together with the first predetermined threshold and the second predetermined threshold
The data can be reset and stored in any of the plurality of second recording means.
If not recorded, copy the data to the first
After copying from the means to any of the second recording means,
The data is transmitted from the second recording means to the transmission means via the network.
It is characterized in that it is controlled to be transmitted to the work .

The first recording means may be a magnetic tape recording / reproducing apparatus, and the plurality of second recording means may be a magnetic disk recording / reproducing apparatus.

[0017]

[0018]

According to the data providing method of the present invention , access from a terminal to data in response to an access request from the terminal is performed.
The request frequency is stored, it is determined whether or not the data is recorded in any of the plurality of first recording means that can be accessed at high speed, and the data is recorded in any of the plurality of first recording means. If so, the data read from the first recording means is transmitted via the network, and the data is
Is recorded in any of the plurality of first recording means,
The frequency of stored access requests to the data
It is equal to or greater than the first predetermined threshold value set in advance.
In this case, if the data among the plurality of first recording means is
Copy to any unrecorded first recording means
Corresponding to the first predetermined threshold and data
Reset the second predetermined threshold that is preset
However , the data is recorded in any of the plurality of first recording means, and the frequency of the stored access request is the first.
2 is less than or equal to a predetermined threshold value, the data is deleted from any one of the first recording means that records the data, and the first predetermined threshold value and the second predetermined threshold value are re-recorded. Set and day
Data is not recorded in any of the plurality of first recording means.
If not, the data is transferred from the large capacity second recording means to
After copying to any of the first recording means, the data
Is read from the first recording means, and is read via the network.
It is characterized by transmitting .

[0020]

In the data providing apparatus and method of the present invention, an end for data in response to an access request from a terminal is provided.
The frequency of the last access request is stored, and when there is an access request for data from the terminal, it is determined whether or not the data is recorded in any one of a plurality of high-speed recording means, and the data is recorded in a plurality of high-speed data. If the data is recorded in any of the recording means , the data is read from the high-speed recording means. In addition , multiple recording devices with high-speed data
Any recorded and recorded actions on any of the columns
The frequency of process requests is preset for the data.
If the data is higher than the first predetermined threshold,
Data is not recorded among multiple recording methods
While being copied to a high-speed recording means which is slightly off,
Pre-set corresponding to the predetermined threshold and data
The second predetermined threshold value that has been set is reset. further,
If the data is recorded in any one of the plurality of high-speed recording means and the frequency of the stored access request is less than or equal to the second predetermined threshold value, the data is recorded. Kano data from the high-speed recording means is removed, first at <br/> constant threshold, and the second predetermined threshold is re-set. Well
In addition, the data is recorded on any of the multiple high-speed recording means.
If not, the data is a large-capacity recording means.
, And then copied to one of the fast recording means,
Data is read from high-speed recording means
Be sent via . Therefore, it is possible to provide the data according to the user's request in real time and at low cost.

[0021]

FIG. 1 shows the configuration of a first embodiment of a video server system for providing a video on demand service, to which the data server system of the present invention is applied. In this video server system, for example, when the terminal 81 or the like is operated to request access to desired data (for example, movie data or the like), the data is M
From O disk array 2 to WS (workstation)
21, via the exchange 61 and the network 71,
It is adapted to be supplied to the terminal 81. Note that FIG.
In (the same applies to FIGS. 4 and 8 to be described later), the data can be provided to the user from the tape streamer 1 through the WS 11, but the provision of the data through this route is particularly important. This is performed only in the case of an emergency, etc. Normally, data is provided from the MO disk array 2 as described above.

The tape streamer 1 is recorded with a movie library formed of data (video data and audio data) of movies, for example, as an information source. The tape streamer 1 includes an MO disk array 2 (MO
Disk array 3 (Fig. 4)) and magnetic disk array 4
Compared with (FIG. 8), the access time is long and the throughput is low, but the cost is low. Therefore, a large capacity tape streamer 1 is used.
A number of movie libraries that users are likely to request access to have been recorded. Tape Streamer 1
A movie library is stored as a backup, so to speak.

The tape streamer 1 is a W that can be processed at high speed.
It is connected to S11. The WS 11 is a ROM that stores a predetermined program, a CPU that performs processing based on the program stored in the ROM, a large-capacity RAM that temporarily stores data necessary for operating the CPU and other data, and a tape. Streamer 1, management server 51,
Alternatively, it is composed of an I / F (interface) (communication interface) that manages input / output of data to / from each of the exchanges 61, and according to the control of the management server 51
Data is read from the tape streamer 1 and supplied to the WS 21. In addition, WS11 (WS2
1 is also the same) can be replaced with another computer.

The WS21 is constructed similarly to the WS11,
According to the control of the management server 51, the tape streamer 1
The data supplied from WS through WS11 can be accessed at high speed and randomly, and high throughput M
Recording (writing) on the O disk array 2 and MO recording
The data recorded in the disk array 2 is read out and output to the exchange 61. Furthermore, WS
Reference numeral 21 is also designed to delete the data recorded in the MO disk array 2 under the control of the management server 51. Note that the WS 21 stores the data to be read from and written to the MO disk array 2 in a large-capacity RA included therein.
It is designed to be temporarily stored in M.
Reading and writing of data with respect to the O disk array 2 can be processed at high speed.

Upon receiving an access request for data from the user terminal 81 or the like, the management server 51 determines whether or not the requested data is recorded in the MO disk array 2, and the data is When recorded on the MO disk array 2, the WS 21 is controlled to read the data from the MO disk array 2. Further, the management server 51
The data requested for access is the MO disk array 2
If the data is not recorded on the disk, the data is copied from the tape streamer 1 to the MO disk array 2 (this is done by issuing an instruction to the WS 11 and 21), and then the data is written to the WS 21. The control for reading from the disk array 2 is performed.

Further, the management server 51 has a memory 52 for storing a frequency management table (FIGS. 2 and 5) which will be described later, and based on the frequency management table, the WS 21 stores M
The control for deleting the data recorded in the O disk array 2 is also performed.

The management server 51, WS 11 and 2
1 is connected by, for example, a coaxial cable, an optical fiber, or a twisted pair wire, and is a LAN (Local Area Network).
rk) is formed.

The exchange 61 sends the data read from the MO disk array 2 via the WS 21 to the terminal (for example, the terminal 81 etc.) that has made an access request for the data via the network 71. Has been done. Also, when a data access request is issued from the terminal 81 via the network 71, the exchange 61 sets a link between the terminal 81 and the WS 21 (performs call setting), and at the same time requests a data access. The management server 51 is also notified of the occurrence.

The network 71 is, for example, a public network (for example, B-ISDN or the like), an ATM network, a high speed LAN, a CATV network, etc., and a terminal 81 and other terminals are connected thereto.

The type of the network 71 determines the specifications of the I / F incorporated in the exchange 61 and the WS 21 (the same applies to the WS 11). That is, the network 71
However, in the case of, for example, an ATM network, the exchange 61 must be an ATM exchange (a switch that performs call setup (call connection) according to the call control procedure of ATM), and the I / F of the WS 21 is an ATM. Interface (A
It must be an interface for managing communication according to the call control procedure of TM. In addition, network 7
If 1 is, for example, ISDN, the exchange 61
ISDN exchange (according to the call control procedure of ISDN,
It is necessary to set it as an exchange that performs call setting (call connection).
The S21 I / F is an ISDN interface (ISD
It must be an interface for managing communication according to the N call control procedure).

Next, FIG. 2 shows an example of the frequency management table stored in the memory 52. In this frequency management table, a unique ID (identification number), which is assigned in advance for each movie data (movie library) that is the information recorded in the tape streamer 1, and a lower limit request for each movie data. The frequency and the information request frequency are stored.

The information request frequency is, for example, the number of times an access request is made to the data of each movie (the total number of access requests to the data of each movie), and as described above, the exchange 61 accesses the movie data. When the management server 51 is notified that there is a request, the management server 51 updates (sets again). The lower limit request frequency is
As will be described later, this is a so-called threshold value that determines whether or not to delete the movie data recorded in the MO disk array 2, and is set in advance by the system designer or the like. When the information request frequency is set to the number of times each data access request is made as described above, the value does not change or only increases with the passage of time (there is no decrease. ), The management server 51 is configured to update the lower limit request frequency with the lapse of time (for example, it is increased by a predetermined constant increase amount).

Next, referring to the flowchart of FIG.
The operation will be described. First, in step S1, the user operates the terminal 81 or the like to make an access request for data of a desired movie. Terminal 8
The access request from 1 is sent via the network 71.
It is input to the exchange 61, and the exchange 61 establishes a link with the terminal 81. Further, in the exchange 61, the fact that the access request has been issued from the terminal 81 indicates that the management server 5
Be informed.

Then, in step S2, it is determined whether or not the data (information) requested to be accessed by the terminal 81 is recorded only in the tape streamer 1 (whether or not it is recorded in the MO disk array 2). But the management server 5
It is judged by 1. Note that this determination is made by the management server 5
1 is performed by causing the WS 11 or 21 to check the recorded contents of the tape streamer 11 or the MO disk array 2.

If it is determined in step S2 that the data requested for access is recorded only in the tape streamer 1, that is, if the data is not recorded in the MO disk array 2, the process proceeds to step S3. The management server 51 copies the data from the tape streamer 1 to the MO disk array 2, for example, at high speed. This is performed by the management server 51 controlling the WSs 11 and 21.

That is, the data for which an access request has been made is data that has never been requested before, or the data has a low information request frequency,
If the data is deleted from the MO disk array 2 in step S7 described later, the data is copied from the tape streamer 1 to the MO disk array 2.

After the copying is completed, the process proceeds to step S4, the exchange 61 establishes a link with the WS 21,
As a result, the communication between the terminal 81 and the MO disk array 2 is made possible. Then, the management server 51 controls the WS 21 so that the data requested to be accessed is read from the MO disk array 2 in response to the operation of the terminal 81, whereby the video-on-demand service is started. It

That is, since the MO disk array 2 can be randomly accessed, can be accessed at a higher speed, and has a high throughput, the data requested by the user can be read out immediately (in real time) to the user. Provided. When the terminal 81 is operated to perform special reproduction of a movie, data is read so that the special reproduction is performed.

Before and after the start of the video on demand service (before, after, or at the same time), the description content of the frequency management table (FIG. 2) stored in the built-in memory 52 of the management server 51. Will be updated. That is, in this case, the information request frequency of the data requested to be accessed is updated (reset). Specifically, for example, if the number of times of requesting access to the data is N times, which is the information request frequency of the data of which access is currently requested, it is incremented by 1. Is updated to N + 1.

After that, when the terminal 81 is operated to end the access request for the data, the service provision is ended, and the processing is ended.

On the other hand, in step S2, when it is judged that the data requested to be accessed is not recorded only in the tape streamer 1, that is, the data is recorded not only in the tape streamer 1 but also in the MO disk array 2. If it is recorded, the process proceeds to step S5, and the same processing as that of step S4 described above is performed. That is, the video-on-demand service is provided and the information request frequency is updated.

After that, when the service provision is completed, the process proceeds to step S6, and the management server 51 causes the memory 5
The frequency management table (FIG. 2) stored in No. 2 is referred to, and the information request frequency of the data for which the access request is currently made (the information request frequency associated with the ID of the data)
Is less than or equal to the lower limit request frequency of the data (lower limit request frequency associated with the ID of the data). If it is determined in step S6 that the data information request frequency is not less than or equal to the lower limit request frequency, the process ends. If it is determined in step S6 that the data information request frequency is less than or equal to the lower limit request frequency, the process proceeds to step S7, the data is deleted from the MO disk array 2, and the process ends.

In other words, in the processing of steps S6 and S7, if the data requested to be accessed has been requested to be accessed less than the lower limit request frequency including the current access, That is, if the data is rarely accessed, the data is transferred to the MO that is more expensive than the tape streamer 1.
Since it is useless to keep the data recorded in the disk array 2 from the viewpoint of its utilization efficiency, such data is deleted from the MO disk array 2 after the service ends.

On the other hand, when the data requested to be accessed has been requested to be accessed more times than the lower limit request frequency including the current access, that is, the data is frequently accessed. If so, the data should be deleted from the MO disk array 2, and then, each time an access request is made, the data must be copied from the tape streamer 1 to the MO disk array 2. The load on the management server 51, the WS 11 and the WS 21 increases, and the time from the access request to the start of the service becomes longer.

Therefore, as described above, data frequently requested to be accessed is copied from the streamer 1 to the MO disk array 2 and then left as it is recorded in the MO disk array 2. As a result, the load on the management server 51, the WS 11 and the WS 21 can be reduced, and the time lag from the access request to the start of the service can be shortened.

Specifically, when the description content of the frequency management table stored in the memory 52 is as shown in FIG. 2, for example, when an access request is made to the data of the information ID # 1 (after ), Since the information request frequency (1 time) of the data is not lower than the lower limit request frequency (0 times), the data is left recorded in the MO disk array 2. Further, for example, when an access request is made to the data of the information ID # 2, the information request frequency (1 time) of the data is equal to or lower than the lower limit request frequency (5 times), so the data is deleted from the MO disk array 2. To be done. Further, for example, when an access request is made to the data of information ID # 3, the information request frequency (5 times) of the data is not less than or equal to the lower limit request frequency (2 times).
It is left recorded on the MO disk array 2.

As described above, many movie libraries are
Since the recording is performed on the inexpensive tape streamer 1 having a large capacity, it is not necessary to provide an expensive recording medium having such a large capacity and which can be accessed at high speed, thus preventing the cost of the system from increasing. can do. Further, since the data requested to be accessed is copied to the MO disk array 2 which can be accessed at high speed, the data requested by the user can be provided in real time. Further, since the data is deleted from the MO disk array 2 in accordance with the data information request frequency, the MO disk array 2 which is a recording medium more expensive than the tape streamer 1 has a small capacity. Also, it can be effectively used.

The data of each movie recorded on the tape streamer 1 may be compressed (for example, MPEG2 compliant). In this case, more movie data can be recorded in the tape streamer 1, and the time required for copying from the tape streamer 1 to the MO disk array 2 can be shortened. When the compressed data is recorded in the tape streamer 1, the decompression process may be performed by the WS 21 or the user terminal 81.

Further, the lower limit request frequency shown in FIG. 2 (the same applies to FIG. 5 described later) is set for each data (information), but in addition to this, for example, for all data,
It is also possible to set it to a constant value.

Further, the information request frequency is the total number of access requests for each data, but in addition to this, for example, the total number of access requests for each data during a predetermined period before the present time, that is, a predetermined number for each data is determined. It can be the total number of access requests within a period. However, when the information request frequency is set to the total number of access requests within a predetermined period, the lower limit request frequency must be set correspondingly (however, in this case, the lower limit request frequency Does not need to change over time as described above).

Furthermore, the deletion of data from the MO disk array 2 is performed after the access request for the data is made.
The information request frequency is referred to, and when the information request frequency is less than or equal to the lower limit request frequency, in this case, when the information request frequency of each data becomes large, the recording capacity of the MO disk array 2 becomes large. Full, tape streamer 1
There is a risk that new data cannot be copied from the MO disk array 2 to the MO disk array 2.

Therefore, as described above, when the data information request frequency is equal to or lower than the lower limit request frequency, the data is not deleted but, for example, when new data is copied to the MO disk array 2. Of the data currently recorded in the MO disk array 2, at least one data request frequency is set to at least one (for example, the data request frequency is the lowest, or the data request frequency is the lowest, and Small data), MO
It may be deleted from the disk array 2.

Alternatively, each time a predetermined time elapses,
It is also possible to update the lower limit request frequency to a large value stepwise (or to increase the increase amount of the lower limit request frequency) and delete the data from the MO disk array 2. In other words, in this case, even if the information request frequency is higher than the lower limit request frequency at a certain point in time, as soon as the number of access requests decreases thereafter, the information request frequency is immediately below the updated lower limit request frequency. As a result, the data will be deleted.

Further, deletion of data from the MO disk array 2 is performed after an access request for the data is made or before new data is copied to the MO disk array 2, or at the management server 51, for example. It can be done at the timing of.

That is, for example, access is concentrated on the data of movies that are now popular, but when the time passes, the number of accesses also decreases. Therefore, for example, when there are few access requests for each data recorded in the MO disk array 2 within a predetermined period (a period from the present time to a predetermined period before), the lower limit request frequency is increased stepwise to a large value. Based on the magnitude relation between the information request frequency of the data and the updated lower limit request frequency, the update is performed (or the increase amount is increased).
The data can be deleted from the MO disk array 2. In this case, whether or not to delete the data from the MO disk array 2 is determined by the number of access requests at the present time.
The utilization efficiency of the disk array 2 can be further improved.

By the way, in the video server system of FIG. 1, there is an upper limit to the number of terminals that can access the MO disk array 2 at the same time (this upper limit will be referred to as "line accommodation capacity" hereinafter). For example, when access requests to the data of a popular movie are concentrated, the access requests exceeding the line capacity must be rejected, which causes the user to wait.

In such a case, the tape streamer 1
Although it may be possible to provide access via the WS 11, this makes it difficult to provide sufficient services as described above.

Therefore, for example, as shown in FIG. 4, an MO disk array 2 that can be accessed at high speed, and
The video server system is configured by providing two or more parts, which are so-called interfaces WS21. It should be noted that how many such parts are provided is determined based on, for example, the number of users.

FIG. 4 shows the configuration of a second embodiment of a video server system to which the present invention is applied. The video server system shown in FIG. 1 is configured similarly to the MO disk array 2 or WS21. The MO disk array 3 or WS31 is provided.

In this video server system, the memory 52 stores a frequency management table as shown in FIG. 5, for example. In this frequency management table, the ID of each movie data described in FIG. 3, the lower limit request frequency and the information request frequency, and the upper limit request frequency are described.

As will be described later, the upper limit request frequency for each data is, so to speak, a threshold value which determines whether or not the movie data copied to the MO disk array 2 is further copied to the MO disk array 3, which is, so to speak, beforehand. It is set by the system designer. The upper limit request frequency is also the same as the lower limit request frequency described above.
1 is set so that it is updated over time (for example, it is increased by a predetermined constant increment).

In this system, for example, as shown in the flowchart of FIG. 6, steps S11 to S14 are performed.
Then, the same processing as that of each of steps S1 to S4 shown in FIG. 3 is performed. In step S12,
When it is determined that the data requested to be accessed by the terminal 81 is recorded only in the tape streamer 1, that is, when the data is not recorded in either the MO disk array 2 or the MO disk array 3, In step S13, the data is transferred from the tape streamer 1 to the MO disk array 2 and the MO disk array 3
Will be copied to either one of. In this case, in the present embodiment, data is transferred from the tape streamer 1 to the MO disk array 2 and the MO disk array 3,
For example, it is assumed that the data is copied to the MO disk array 2.

On the other hand, in step S12, when it is judged that the data requested to be accessed is not recorded only in the tape streamer 1, that is, the data is recorded not only in the tape streamer 1 but also in the MO disk array 2. If recorded, or if recorded not only on the tape streamer 1 but also on the MO disk arrays 2 and 3, the process proceeds to step S15 and step S in FIG.
As described in 4, the information request frequency of the data is updated (reset).

Then, in step S16, the memory 5
The frequency management table (FIG. 5) stored in No. 2 is referred to, and whether or not the information request frequency of the data for which access is currently requested is higher than the lower limit request frequency of the data and lower than the upper limit request frequency of the data. Is determined. When it is determined in step S16 that the information request frequency of the data for which the access request has been made is greater than the lower limit request frequency and less than the upper limit request frequency, that is, the number of access requests for the data is not particularly small. ,
If the number is not particularly large, the process proceeds to step S17, and FIG.
The service is provided as described in step S4 of
The process ends.

In this case, as described above, the access-requested data may be recorded only in the MO disk array 2 or both of the MO disk arrays 2 and 3. If the data requested for access is recorded only in the MO disk array 2, the terminal (terminal requesting access) 81
A link is established so that the O disk array 2 can be accessed. When the data requested to be accessed is recorded in both MO disk arrays 2 and 3, basically, the data is first copied from the tape streamer 1 of the MO disk arrays 2 and 3. A link is established with the MO disk array 2 which is the one to be processed, but when the number of access requests that are currently occurring exceeds the line capacity, the tape is processed in step S22 (FIG. 7) described later. A link is established with the MO disk array 3 from which the data is copied from the streamer 1. That is, in this case, the optimum allocation of the MO disk array 2 or 3 to the terminal 81 is performed according to the number of access requests that are occurring now.

On the other hand, if it is determined in step S16 that the information request frequency of the data for which access is currently requested is equal to or lower than the lower limit request frequency or equal to or higher than the upper limit request frequency, the process proceeds to step S21 in FIG. It is determined whether or not the information request frequency of the data requested for access is equal to or higher than the upper limit request frequency. If it is determined in step S21 that the information request frequency of the data currently requested for access is equal to or higher than the upper limit request frequency, that is, the data currently requested for access is, for example, data of a popular movie, When the number of access requests is very large and the number approaches the line accommodation capacity of the MO disk array 2, the process proceeds to step S22 and the data is copied to the MO disk array 3 under the control of the management server 51. At the same time, the provision, that is, the service is started (provided that the data is already recorded in both the MO disk arrays 2 and 3, that is, when an unexpected number of access requests occur simultaneously. , Some users will have to wait until the line is free).

The copying of this data may be performed from the tape streamer 1 or the MO disk array 2.

Then, the upper limit request frequency stored in the frequency management table of the data copied to the MO disk array 3 is updated (reset). That is, by copying the data to the MO disk array 3,
Even if the line capacity for the data increases (in this case, it doubles), if the upper limit request frequency is left unchanged, then each time there is an access request for the data, The data will be copied (in the system of FIG. 4, since there are only two MO disk arrays, MO disk arrays 2 and 3, M
After the copy is made to the O disk array 3, no further copy is made, but if there are three or more MO disk arrays, the above copy will be made).

Since this wastes resources (MO disk array), in order to prevent this, the data is
After copying to the disk array 3, the upper limit request frequency of the data is updated to a large value (reset).
(Or, it is updated so that the increase amount of the upper limit request frequency becomes large).

Further, in this case, the lower limit request frequency is also updated (reset). That is, by copying the data to the MO disk array 3, the line capacity for the data increases as described above.
When the access requests for the data are reduced, the MO disk array 3 is used from the viewpoint of effective use of resources.
It is preferable to delete the data copied to. Therefore, when the number of access requests to the data copied to the MO disk array 3 becomes small, the value of the lower limit request frequency is updated to a large value so that the data is deleted in step S24 described later (or ,
Updated to increase the lower limit request frequency).

After the service has been provided, the process is completed.

On the other hand, if it is determined in step S21 that the information request frequency of the data currently requested for access is not higher than the upper limit request frequency, that is, the information request frequency of the data currently requested for access is the lower limit request frequency. In the case of the following, the process proceeds to step S23, and service provision is started. Then, when it ends, step S24
Then, the data requested to be accessed is deleted from the MO disk array 2 or 3.

That is, the data requested to be accessed is M
When recorded in both the O disk arrays 2 and 3, the data is deleted from the MO disk 3 to which the data was copied later. Further, the data requested to be accessed is the MO disk arrays 2 and 3.
If the data is recorded only in the MO disk array 2, the data is deleted from the MO disk array 2.

As described above, when the information request frequency of the data which has been requested to be accessed is low, the data is deleted from the MO disk array 2 or 3.

After that, the upper limit request frequency and the lower limit request frequency stored in the frequency management table of the memory 52 are updated (reset), and the process ends. That is, the upper limit request frequency and the lower limit request frequency of the deleted data are updated to small values (or updated so that the increase amounts of the upper limit request frequency and the lower limit request frequency are small), and the process is ended.

Therefore, in this case, the same effect as in the case of FIG. 1 can be obtained, and even if the access requests for certain data are concentrated, the user does not have to wait.
Can provide services.

The upper limit request frequency in the video server system shown in FIG. 4 (the same applies to FIG. 8 described later) is as shown in FIG.
The handling can be changed in the same manner as the lower limit request frequency described in.

That is, the upper limit request frequency can be set to a constant value for all data of each movie. further,
The upper limit request frequency can be set corresponding to the information request frequency when the information request frequency is the total number of access requests for each data for a predetermined period from the present time (in this case, , It is not necessary to change the upper limit request frequency with the passage of time as described above).

Data is not copied to the MO disk array 3 when an access request for the data is made, but in the same manner as the above-mentioned data deletion.
It is possible to cause the management server 51 to perform it at an arbitrary timing.

Furthermore, the video server system of FIG.
In the system shown in FIG. 1, only one MO disk array (MO disk array 3) is added and configured.
Besides this, it is also possible to add two or more MO disk arrays. The number of users who can access at the same time can be increased by constructing the system with more MO disk arrays, but how many MO disk arrays are provided depends on the number of users who can access at the same time. It is preferable to make a decision in consideration of the balance between the cost and the cost.

Further, as the recording medium which can be accessed at high speed, in addition to the MO disk array, for example, a magnetic disk array can be used. Magnetic disk array
Since the access time is shorter than that of the MO disk array (about 1/5), by using this, it becomes possible to respond to the user's request in a shorter time. Further, since the magnetic disk array has a higher throughput than the MO disk array, as will be described later, the line capacity is large, and therefore the number of simultaneously accessible users can be increased. However, the recording capacity of the magnetic disk array is smaller than that of the MO disk array (about 1/100), and the magnetic disk array is more expensive than the MO disk array. The use of the disk array makes it possible to configure the system at a lower cost than the case of using the magnetic disk array.

Further, as the recording medium which can be accessed at high speed, both the MO disk array and the magnetic disk array having a shorter access time can be used.

FIG. 8 shows the configuration of a third embodiment of a video server system to which the present invention is applied. The video server system shown in FIG. 4 has a magnetic disk array 4 and a W disk.
WS41 configured similar to S11 (WS21, 31)
It is supposed to be provided.

In this case, a copy of the data (management server 5
1) is performed sequentially with respect to the MO disk arrays 2 and 3 having a long access time and then to the magnetic disk array 4 having a short access time as the number of access requests for the data increases. Done.

That is, when the number of accesses increases, when the data cannot be dealt with by simply copying the data to the MO disk arrays 2 and 3, copying to the magnetic disk array 4 is performed.

Here, in each of the MO disk arrays 2 and 3 or the magnetic disk array 4, when there are a plurality of access requests, the reading of the data corresponding to the access requests is performed in a time division manner.

As described above, the magnetic disk array 4 has a smaller recording capacity than the MO disk arrays 2 and 3, but has a short access time and therefore has a higher throughput.

Therefore, assuming that the MO disk arrays 2 and 3 can handle, for example, 10 simultaneous access requests, the magnetic disk array 4 can handle more simultaneous access requests, such as 20 and 30 simultaneous access requests. Since it is possible to deal with this, according to the system shown in FIG. 8, the same effect as that of the system of FIGS. 1 and 4 can be obtained, and at the same time,
Even if the access requests increase enormously, the service can be provided without making the user wait.

In FIG. 8, the magnetic disk array is
Although only one is provided, it is also possible to provide two or more.

The case where the present invention is applied to the video server system for performing the video on-demand service for movies has been described above. The present invention, in addition to such a server system, audio, text and other data, or those data. It can be applied to any data server system that provides multimedia data in which video is combined with.

In this embodiment, the information request frequency of data is managed for each data recorded in the tape streamer 1. However, in addition to this, in the system shown in FIG. MO disk array 2
It is also possible to separately manage the information request frequency of the data recorded on the disk and the information request frequency of the data recorded on the MO disk array 3.

[0092]

As described above, according to the present invention, it is possible to provide data in response to a user's request in real time and at low cost.

[Brief description of drawings]

FIG. 1 is a first video server system to which the present invention is applied.
It is a figure which shows the structure of an Example.

FIG. 2 is a diagram showing an example of a frequency management table.

FIG. 3 is a flowchart illustrating the operation of the embodiment of FIG.

FIG. 4 is a second video server system to which the present invention is applied.
It is a figure which shows the structure of an Example.

FIG. 5 is a diagram showing an example of a frequency management table.

6 is a flowchart illustrating the operation of the embodiment of FIG.

FIG. 7 is a flowchart following the flowchart of FIG.

FIG. 8 is a third video server system to which the present invention is applied.
It is a figure which shows the structure of an Example.

FIG. 9 is a diagram showing a configuration of an example of a conventional video server system.

[Explanation of symbols]

1 tape streamer 2,3 MO disk array (magneto-optical disk array) 4 magnetic disk array 11,21,31,41 workstation (WS) 51 Management server 52 memory 61 Exchange 71 network 81 terminals

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-123438 (JP, A) JP-A-5-46668 (JP, A) JP-A-2-239319 (JP, A) JP-A-6- 119383 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G06F 17/30-17/30 419 G06F 12/00 501 H04N 7/173 610

Claims (3)

(57) [Claims] 1. A data providing apparatus for providing data in response to an access request from a terminal via a network, which can be accessed at high speed with a large-capacity first recording unit in which the data is recorded. A plurality of second recording means, a plurality of read / write control means for reading / writing data from / to each of the plurality of second recording means, and a read / write control means for reading from the corresponding second recording means. The transmitting means for transmitting the generated data to the terminal via the network, and whether or not the data requested to be accessed by the terminal is recorded in any of the plurality of second recording means. judgment, be stored and determining control means for <br/> control of the transmission of the data based on the determination result, the frequency of access requests from the terminal for the data Storage means and, said the judgment control unit, said data a plurality of the second
And the frequency of the access request stored in the storage means is equal to or less than a first predetermined threshold value set in advance corresponding to the data. In some cases, the data is deleted from any of the second recording means that records the data , and the first predetermined threshold value and the data are handled.
And a resetting means for resetting a preset second predetermined threshold value , wherein the determination control means stores the data in any one of the plurality of second recording means.
If it has been recorded, the transmission is performed from the second recording means.
Sending the data to the network via communication means
Control so that the data is recorded in any one of the plurality of second recording means.
Is recorded and stored in the storage means.
The frequency of access requests is greater than or equal to the second predetermined threshold value.
In this case, the data is stored in the plurality of second recording means,
Any of the above-mentioned second records in which the above-mentioned data is not recorded.
While copying to the recording means, the first predetermined threshold value and
And resetting the second predetermined threshold value so that the data is recorded in any of the plurality of second recording means.
If it is not recorded, the data is recorded in the first record.
Copy from the recording means to any of the second recording means
Then, from the second recording means through the transmitting means,
A data providing apparatus, characterized by controlling to transmit the data to the network . 2. The data according to claim 1, wherein the first recording means is a magnetic tape recording / reproducing apparatus, and the plurality of second recording means are magnetic disk recording / reproducing apparatuses. Providing device. 3. The over the network, the data providing method for providing data in response to an access request from the terminal, before for the data corresponding to the access request from the terminal
Storing the frequency of access requests from the serial terminal, the data may determine whether it is recorded in either the first recording means a plurality accessible at high speed, the data is plural first When recorded in any one of the recording means, the data read from the first recording means is transmitted via the network, and the data is stored in any one of the plurality of first recording means. Record
The frequency of the access requests recorded and stored.
Degree is preset for the data
1 is greater than or equal to a predetermined threshold value, the data is
Note that the data is not recorded in the first recording means.
Copying to any one of the first recording means
Corresponding to the first predetermined threshold and the data
Reset the second predetermined threshold that is preset
However , when the data is recorded in any of the plurality of first recording means and the frequency of the stored access request is equal to or less than the second predetermined threshold value, the data is recorded. Deleting the data from any one of the first recording means, the first predetermined threshold value , and
The second predetermined threshold value is reset and the data is recorded in any of the plurality of first recording means.
If it is not recorded, the above data should
From one of the first recording means.
After that, the data is read from the first recording means.
And transmitting the data via the network .