JP3186045B2 - Magnetic tape device embedded control method in multi-host system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape device embedding control method in a multi-host system, and more particularly to a magnetic tape device embedding control method in a multi-host system in which a plurality of hosts share a magnetic tape device.

[0002]

2. Description of the Related Art Conventionally, in this type of multi-host system, when a magnetic tape device is installed in a host (registered in the host to make the magnetic tape device usable by the host), the magnetic tape device is In order to recognize the magnetic tape loaded in the magnetic tape device, it is necessary to obtain medium control information (medium name, medium standard information) recorded at the head of the magnetic tape, and the magnetic tape is rewound. I was

For this reason, if an attempt is made to incorporate a magnetic tape device assigned to another host (used by another host) into the host itself, the position of the magnetic tape is incorrectly determined during data input / output of the other host. Therefore, it is impossible to incorporate a magnetic tape device in a plurality of hosts because the data input fails or the head of the magnetic tape is destroyed by the data output (NEC Corporation,
Guide to the Use of Cartridge Magnetic Tape, October 1994
Month, 2nd edition, page 83, shared by multiple systems).

[0004]

A first problem is that when a magnetic tape device assigned to another host is to be incorporated into the host itself, data input from the other host fails or data output from the magnetic tape unit fails. That is, the beginning of the tape is destroyed. The reason is that since the medium control information of the magnetic tape is recorded at the head of the magnetic tape, it is necessary to locate the head of the magnetic tape when acquiring the medium control information when the magnetic tape device is incorporated.

SUMMARY OF THE INVENTION It is an object of the present invention to use a magnetic tape device on its own host even when a magnetic tape on the magnetic tape device is assigned (used) by its own host and the magnetic tape device is installed on another host. It is an object of the present invention to provide a control method for assembling a magnetic tape device in a multi-host system so as not to affect the operation.

[0006]

According to the present invention, there is provided a magnetic tape device embedding control method in a multi-host system, comprising: a multi-host system in which a magnetic tape device is shared by a plurality of hosts; A global device management table provided on the data recording device for managing media control information, host device built-in information and host device assignment information; and a media control recorded at the head of a magnetic tape loaded in the magnetic tape device. A medium recognizing means for reading information; and, when a request for mounting the magnetic tape device to the host is made, if the host is the first built-in host, the medium recognizing means controls the medium from the magnetic tape loaded in the magnetic tape device. Read the information, record it in the global device management table, and If the host is not the first built-in host, the device built-in means for acquiring medium control information from the global device management table; and When the magnetic tape device is allocated to another host, the magnetic tape device is put on standby, and when the magnetic tape device is not allocated to another host, the host device allocation information in the global device management table contains the magnetic tape device. A device allocating means for recording that the magnetic tape device is being allocated by the host; and a magnetic tape device being allocated by the host based on the host device allocation information in the global device management table at the time of a request to release the magnetic tape at the host. Device release means for deleting the fact that To.

Further, in the multi-host system according to the present invention, a control method for assembling a magnetic tape device in a multi-host system is provided in a multi-host system in which one or more magnetic tape devices are shared by a plurality of hosts. A global device management table provided on the data recording device for managing, for each magnetic tape device identifier, a record comprising medium control information, host device built-in information, and host device allocation information; and a magnetic device mounted on the magnetic tape device. A medium recognizing means for reading medium control information recorded at the head of the tape, and, when a request for incorporating the magnetic tape device to the host is made, if the host is the first built-in host of the magnetic tape device, the medium recognizing means The media control information is read from the magnetic tape loaded in the magnetic tape device. Device recording means for acquiring the medium control information from the corresponding record of the global device management table, if the own host is not the first built-in host of the magnetic tape device, When a magnetic tape device in which the magnetic tape is mounted is allocated to another host based on the host device allocation information of the corresponding record in the global device management table when a magnetic tape allocation request is issued to the host, When the tape device is waiting for free space, and the magnetic tape device is not allocated to another host, the host device allocation information of the corresponding record in the global device management table indicates that the magnetic tape device is being allocated by the host. Device allocation means for recording, and And a device release means to remove the effect that the at gas tape release request tape drives global device management table the magnetic tape from the host device allocation information of the corresponding record in is loaded is being allocated in the local host.

On the other hand, a recording medium according to the present invention is a computer which is provided with a medium recognizing means for reading medium control information recorded at the head of a magnetic tape loaded in a magnetic tape device, and a computer for transmitting the magnetic tape device to its own host. At the time of the installation request, if the own host is the first embedded host, the medium recognizing means reads the medium control information from the magnetic tape loaded in the magnetic tape device and records it in the global device management table, and the own host is the first embedded host. If the host is not the built-in host, the device mounting means for acquiring the medium control information from the global device management table. If assigned to the host, leave the magnetic tape unit empty. Waiting, and when the magnetic tape device is not allocated to another host, device allocating means for recording in the host device allocation information of the global device management table that the magnetic tape device is being allocated on its own host; and A program for functioning as a device releasing means for deleting the fact that the magnetic tape device is being allocated by the host from the host device allocation information of the global device management table when a request for releasing the magnetic tape at the host is recorded.

Further, the recording medium of the present invention comprises a computer for recognizing medium control information for reading medium control information recorded at the head of a magnetic tape loaded in a magnetic tape device, and incorporating the magnetic tape device into its own host. On request,
If the own host is the first built-in host of the magnetic tape device, the medium recognizing means reads the medium control information from the magnetic tape loaded in the magnetic tape device and records it in the corresponding record of the global device management table. If the host is not the first built-in host of the magnetic tape device, device mounting means for acquiring medium control information from the corresponding record of the global device management table; If the magnetic tape device in which the magnetic tape is loaded is allocated to another host based on the host device allocation information in the record, the magnetic tape device waits for empty space, and the magnetic tape device is allocated to another host. If not, the global device management Device allocation means for recording in the host device allocation information of the corresponding record of the corresponding table that the magnetic tape device is being allocated by the own host, and when the local host requests to release the magnetic tape, A program for functioning as device release means for deleting from the host device allocation information that the magnetic tape device in which the magnetic tape is loaded is being allocated by the host is recorded.

[0010]

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

FIG. 1 is a block diagram showing a configuration of a multi-host system to which a magnetic tape device installation control system according to a first embodiment of the present invention is applied. In this multi-host system, two hosts A and B include one or more magnetic tape devices 6 and an inter-host data recording device 7.
And are configured to share.

Referring to FIG. 2, the inter-host data recording device 7 is provided with a global device management table 70. The global device management table 70 includes, for each magnetic tape device 6, a magnetic tape device identification name, Medium control information for recording the medium name and medium standard information of the magnetic tape loaded in the magnetic tape device 6, host device built-in information for recording the host numbers of all built-in hosts and corresponding built-in flags, As many records as the number of magnetic tape devices 6 are stored, each record including host device assignment information for recording the host number of the assigned host.

Each of the hosts A and B includes a program 1, a device incorporating unit 2, a medium recognizing unit 3, a device allocating unit 4, and a device releasing unit 5.

When the system is installed or when there is a request to install the magnetic tape device 6 using the magnetic tape device identifier as a parameter at system startup or by an operator command, the global device management table 70 uses the magnetic tape device identifier as a key. And records its own host number and a built-in flag (ON) in the host device built-in information of the searched record (hereinafter referred to as a searched record), and the magnetic tape device 6 having the same magnetic tape device identification name It is checked whether or not the magnetic tape device is already installed in another host. If the magnetic tape device is not installed in another host, the magnetic tape device is recorded at the beginning of the magnetic tape loaded in the magnetic tape device 6 by the medium recognizing means 3. The media control information is read and recorded in the searched record, It acquires medium control information from a retrieved records when the tape device 6 has been incorporated into other hosts.

The medium recognizing means 3 rewinds the magnetic tape loaded in the magnetic tape device 6 to perform cueing, and performs medium control information (medium name, medium) recorded at the head (tape head) of the magnetic tape. Standard information).

Upon receiving a magnetic tape allocation request using the medium name as a parameter from the program 1, the apparatus allocating means 4 searches a record in the global apparatus management table 70 using the medium name as a key, and searches the host apparatus for the searched record. It is determined whether or not the own host has been installed on the basis of the embedded information. If the installed host has been installed, the magnetic tape device 6 in which the magnetic tape of the same medium name is loaded is connected to another host based on the host device allocation information of the searched record. It is checked whether or not the magnetic tape device 6 is assigned to the idle state, and if not, the own host number is recorded in the host device assignment information of the searched record. To indicate that the magnetic tape device 6 is being allocated (in use) by its own host.

The device release means 5 receives a request from the program 1 to release the magnetic tape with the medium name as a parameter.
A record of the global device management table 70 is searched using the medium name as a key, the host number is deleted from the host device assignment information of the searched record, and the magnetic tape device 6 to which the magnetic tape having the medium name is loaded is sent to the host. Release the assignment. Thereby, the assignment of the magnetic tape device 6 by another host becomes possible.

Referring to FIG. 3, the processing of the device incorporating means 2 includes a record search step 201, a record presence / absence determination step 202, a local host number and a built-in flag recording step 203, and a local host first built-in host determination step 204. , A medium recognition means calling step 205, a medium control information recording step 206, and a medium control information acquisition step 207.

Referring to FIG. 4, the processing of the medium recognizing means 3 includes a magnetic tape cueing step 301 and a medium name and medium standard information reading step 302.

Referring to FIG. 5, the processing of the device allocating means 4 includes a record search step 401, a record presence / absence determination step 402, a local host built-in determination step 403, and another host allocated determination step 40.
4 and its own host number recording step 405.

Referring to FIG. 6, the processing of the device release means 5 includes a record search step 501, a record presence / absence determination step 502, and a host number deletion step 503.

Next, the operation of the magnetic tape device installation control method in the multi-host system according to the first embodiment configured as described above will be described.

Here, it is assumed that the host into which the magnetic tape device 6 is installed first is the host A.

When the system is started or an operator command causes the host A to request a device to be installed with the magnetic tape device identifier as a parameter, the device incorporating means 2 of the host A uses the magnetic tape device identifier as a key. A record is searched from the global device management table 70 on the inter-host data recording device 7 (step 20).
1) If there is no corresponding record (No in step 202), it is determined that the device installation has failed.

If there is a corresponding record (step 20)
2), the device incorporation means 2 of the host A records the own host number and the incorporation flag (ON) in the host device incorporation information of the searched record (step 20).
3).

Next, the device incorporating means 2 of the host A
It is determined whether the host A is the first built-in host by referring to the host number and the built-in flag of the host device built-in information of the searched record (step 20).
4). More specifically, if the host number is not other than the host (host A) or if the built-in flags corresponding to all the built-in host numbers are OFF, the host A
Is the first built-in host, and if at least one built-in flag corresponding to the host number of a host other than the host A is ON, it is determined that the host A is not the first built-in host.

If the host A is the first embedded host (Yes in step 204), the device embedding means 2 of the host A calls the medium recognizing means 3 of the host A to acquire the medium control information from the magnetic tape (step 204). Step 20
5).

The medium recognizing means 3 of the host A rewinds the magnetic tape loaded in the magnetic tape device 6 having the same magnetic tape device identification name to perform cueing (step 301).
The medium name and medium standard information recorded at the head of the magnetic tape are read (step 302).

When the processing of the medium recognizing means 3 of the host A is completed, the apparatus incorporating means 2 of the host A records the medium name and the medium standard information obtained by the medium recognizing means 3 in the medium control information of the searched record. (Step 20
6).

After this, or at step 204, host A
Is not the first embedding host, the device embedding means 2 of the host A acquires the medium control information from the searched record (step 207), and completes the embedding of the magnetic tape device 6 into the host A.

When the program 1 of the host A issues a request for allocating a magnetic tape with the medium name as a parameter after the magnetic tape device 6 has been incorporated into the host A, the device allocating means 4 of the host A changes the medium name to A record is searched from the global device management table 70 on the inter-host data recording device 7 as a key (step 401). If there is no corresponding record (no in step 402),
Assignment failed.

If there is a corresponding record (step 40)
2), the device allocating means 4 of the host A refers to the host device installation information of the searched record and determines whether the magnetic tape device 6 for mounting the magnetic tape having the same medium name has been installed in the host (host A). It is determined whether it is (Step 403). More specifically, if the own host number is recorded in the host device installation information of the searched record, and the installation flag corresponding to the own host number is ON, it is determined that the installation is completed, and the host device installation information of the searched record is determined. If the own host number is not recorded, or even if the own host number is recorded, if the built-in flag corresponding to the own host number is OFF, it is determined that the own host number is not installed.

If the magnetic tape device 6 for mounting the magnetic tape having the same medium name has not been installed in the host (host A) (No in step 403), the device allocation means 4 of the host A determines that the allocation has failed.

If the host (Host A) has already installed the host (Yes in step 403), the device allocating means 4 of the host A determines whether or not another host number is recorded in the host device allocation information of the searched record. Then, it is determined whether or not the magnetic tape device 6 is assigned to another host (host B) (in use) (step 404).

If the magnetic tape device 6 has been allocated to another host (host B) (YES in step 404), the device allocation means 4 of the host A determines that the allocation has failed.

If the magnetic tape device 6 has not been allocated to another host (host B) (No in step 404), the device allocating means 4 of the host A stores the host (host) in the host device allocation information of the searched record. A)
The host (host A) displays that the magnetic tape device 6 is being assigned (in use) (step 405), and the assignment is completed.

Thereafter, when there is an apparatus installation request in the host B using the magnetic tape apparatus identification name of the magnetic tape apparatus 6 already installed in the host A as a parameter by an operator command, the apparatus installation means 2 of the host B
Retrieves a record from the global device management table 70 on the inter-host data recording device 7 using the same magnetic tape device identification name as a key (step 201), and if there is no corresponding record (no at step 202), the device installation failure And

If there is a corresponding record (step 20)
2), the device incorporation means 2 of the host B records the own host number and the incorporation flag (ON) in the host device incorporation information of the searched record (step 20).
3).

Next, the device incorporating means 2 of the host B
It is determined whether the host B is the first built-in host by referring to the host number and the built-in flag of the host device built-in information of the searched record (step 20).
4). In this case, since the installation flag corresponding to the host number of the host A is ON, the device installation means 2 of the host B determines that the host B is not the first installation host.

For this reason, the device incorporating means 2 of the host B
Acquires the medium control information from the searched record (step 207), and completes the incorporation of the magnetic tape device 6 into the host B.

As described above, when the host device has the magnetic tape device 6
If the host is not the first built-in host, the magnetic tape device 6 can be built into its own host without the operation of rewinding the magnetic tape and reading the medium control information.
For this reason, even if the same magnetic tape device is installed in the own host while the magnetic tape on the magnetic tape device is allocated (in use) by another host, the use of the magnetic tape device in another host is affected. Never. Therefore, when an attempt is made to incorporate a magnetic tape device assigned to another host into the host itself, there is no danger that data input by the other host will fail or that the head of the magnetic tape will be destroyed by data output.

Thereafter, when a program 1 of the host B issues a magnetic tape allocation request with the medium name of the magnetic tape already requested by the host A as a parameter, the device allocating means 4 of the host B sends the medium name A record is searched from the global device management table 70 on the host-to-host data recording device 7 by using
1) If there is no corresponding record (No in step 402), it is determined that the assignment has failed.

If there is a corresponding record (step 40)
2), the device allocating means 4 of the host B refers to the host device installation information of the searched record to determine whether the magnetic tape device 6 for mounting the magnetic tape having the same medium name has been installed in the host (host B). It is determined whether it is (Step 403). In this case, since the installation flag corresponding to the host number is ON, it is determined that the installation has been completed.

Next, the device allocating means 4 of the host B
It is determined whether the magnetic tape device 6 has been assigned (used) to another host (host A) based on whether or not another host number is recorded in the host device assignment information of the searched record (step). 40
4). In this case, the magnetic tape device 6 is allocated (used) to another host (host A).
Therefore, the device assignment unit 4 of the host B determines that the assignment has failed (waiting for free).

Thereafter, when there is a request from the program 1 of the host A to release the magnetic tape using the medium name as a parameter,
The device release means 5 of the host A is notified.

The device release means 5 of the host A searches the global device management table 70 on the inter-host data recording device 7 for a record using the medium name as a key (step 50).
1) If there is no corresponding record (No in step 502), release is determined to have failed.

If there is a corresponding record (step 50)
2), the device release means 5 of the host A deletes the host number of its own host (host A) from the host device allocation information of the searched record (step 503), and completes the release.

As a result, the magnetic tape device 6 having the magnetic tape device identification name of the searched record is released, and the magnetic tape device 6 can be assigned to another host (host B).

The same processing is performed when the program 1 of the host B issues a request to release the magnetic tape using the medium name as a parameter.

When a system disconnection request is made at the host A by using the magnetic tape device identification name as a parameter at the end of the system or by an operator command, the device embedding means 2 of the host A uses the magnetic tape device identification name as a key for the host A. A record is searched from the global device management table 70 on the interim data recording device 7, the own host number is deleted from the corresponding host device built-in information, and the built-in flag is turned off.

Next, a second embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 7, the control method for assembling the magnetic tape device in the multi-host system according to the second embodiment of the present invention is the same as that of the multi-host system according to the first embodiment shown in FIG. For the tape device embedded control system, a recording medium 8 in which a device embedded control program is recorded for each of the hosts A and B is provided. The recording medium 8 includes a magnetic disk, a semiconductor memory,
Other recording media may be used.

The device built-in control program is stored in the recording medium 8.
From the host A and the host A, respectively.
And B are controlled as device incorporating means 2, medium recognizing means 3, device allocating means 4, and device releasing means 5. The operations of the hosts A and B under the control of the device embedding control program are exactly the same as those in the case of the magnetic tape device embedding control method in the multi-host system according to the first embodiment.

By the way, in each of the above embodiments, the two hosts, the hosts A and B, share the magnetic tape device 6 and the inter-host data recording device 7.
It may be more than one.

Although a plurality of magnetic tape devices 6 are shared by a plurality of hosts, the present invention can be similarly applied to a single magnetic tape device 6.

[0056]

The first effect is that even if the magnetic tape device on the magnetic tape device is allocated (used) by the own host and the magnetic tape device is incorporated by another host, the magnetic tape on the own host is not affected. It does not affect the use of the tape device. The reason is that first, the host incorporating the magnetic tape device reads the medium control information of the magnetic tape loaded on the magnetic tape device and stores the information in the global device management table on the inter-host shared data recording device which can be referred to by each host. Since recording is performed, the host that subsequently incorporates the magnetic tape device can incorporate the magnetic tape device without performing operations such as rewinding and reading to the magnetic tape device by referring to the medium control information in the global device management table. It is.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a magnetic tape device installation control method in a multi-host system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing contents of a global device management table recorded in an inter-host data recording device in FIG. 1;

FIG. 3 is a flowchart showing a process of a device incorporating unit in FIG. 1;

FIG. 4 is a flowchart showing a process of a medium recognizing unit in FIG. 1;

FIG. 5 is a flowchart showing a process of a device assignment unit in FIG. 1;

FIG. 6 is a flowchart showing a process of a device release unit in FIG. 1;

FIG. 7 is a block diagram showing a configuration of a magnetic tape device installation control method in a multi-host system according to a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 program 2 device incorporating means 3 medium recognizing means 4 device allocating means 5 device releasing means 6 magnetic tape device 7 inter-host data recording device 8 recording medium 70 global device management table A, B host

Claims (8)

(57) [Claims] In a multi-host system in which a magnetic tape device is shared by a plurality of hosts, media control information, host device built-in information, and a host device are provided on an inter-host data recording device shared by the plurality of hosts. Global device management table for managing allocation information, medium recognition means for reading medium control information recorded at the head of a magnetic tape loaded in the magnetic tape device, and a request for incorporating the magnetic tape device into its own host Sometimes, if the own host is the first built-in host, the medium recognizing means reads the medium control information from the magnetic tape loaded in the magnetic tape device and records it in the global device management table. If it is not a host, retrieve the media control information from the global device management table. The device incorporating means for obtaining the magnetic tape device when the magnetic tape device is allocated to another host based on the host device allocation information in the global device management table at the time of the request for allocating the magnetic tape to the host; Waiting, and when the magnetic tape device is not allocated to another host, a device allocating unit that records in the host device allocation information of the global device management table that the magnetic tape device is being allocated by the own host, A multi-host, comprising: a device release unit that deletes, from the host device allocation information in the global device management table, that the magnetic tape device is being allocated by the host when a request for releasing the magnetic tape is issued from the host. A control method for incorporating a magnetic tape device in the system. 2. A multi-host system in which one or more magnetic tape devices are shared by a plurality of hosts, the multi-host system being provided on an inter-host data recording device shared by the plurality of hosts, wherein a plurality of magnetic tape devices are provided for each magnetic tape device identifier. Global management table for managing a record including medium control information, host device built-in information, and host device allocation information, and medium recognition for reading medium control information recorded at the beginning of a magnetic tape loaded in a magnetic tape device Means and at the time of requesting the incorporation of the magnetic tape device into its own host,
If the host is the first built-in host of the magnetic tape device, the medium recognizing means reads medium control information from the magnetic tape mounted on the magnetic tape device and records the medium control information in a corresponding record of the global device management table, If the own host is not the first built-in host of the magnetic tape device, device incorporating means for acquiring medium control information from the corresponding record of the global device management table; and the global device management table when a request for allocating a magnetic tape to the own host is made. If the magnetic tape device in which the magnetic tape is loaded is assigned to another host based on the host device assignment information of the corresponding record, the magnetic tape device waits for an empty space, and the magnetic tape device The global device if not assigned Device allocation means for recording in the host device allocation information of the corresponding record of the corresponding record in the management table that the magnetic tape device is being allocated by the own host, and the corresponding record of the global device management table upon request of releasing the magnetic tape by the own host Device release means for deleting from the host device allocation information that the magnetic tape device in which the magnetic tape is loaded is being allocated by its own host, and a magnetic tape device embedding control method in a multi-host system. . 3. The global device management table includes a magnetic tape device identification name, media control information including a media name and media standard information of a magnetic tape loaded in the magnetic tape device, host numbers and host numbers of all hosts. 3. A magnetic tape in a multi-host system according to claim 1, wherein a record comprising host device installation information comprising a corresponding installation flag and host device allocation information comprising a host number of an assigned host is stored. Device embedded control method. 4. The host-to-host data processing system according to claim 1, wherein the device incorporation means uses the magnetic tape device identification name as a key when the system is started or when there is a device installation request using the magnetic tape device identification name as a parameter by an operator command. The record is searched from the global device management table on the recording device, the own host number and the built-in flag are recorded in the host device built-in information of the searched record, and the host number and the built-in flag of the host device built-in information of the searched record are referenced. It is determined whether or not the host itself is the first embedded host, and if the host is the first embedded host, the medium is recognized from the magnetic tape loaded in the magnetic tape device having the same magnetic tape device identifier by the medium recognizing means. The control information is read and recorded in the searched record, 3. The method according to claim 1, wherein the medium control information is obtained from the searched record unless the host is the first embedded host. 5. The apparatus allocating means retrieves a record from a global device management table on the inter-host data recording device using the medium name as a key when a magnetic tape allocation request using the medium name as a parameter is received. Then, referring to the built-in flag corresponding to the own host number of the host device built-in information of the searched record, it is determined whether or not the magnetic tape device for loading the magnetic tape of the same medium name has been built in the own host, and If the magnetic tape device in which the magnetic tape is loaded is already installed in the host, the magnetic tape device is allocated to the other host based on whether or not another host number is recorded in the host device allocation information of the searched record. Is determined, and if the magnetic tape device is not assigned to another host, the searched record 3. The magnetic tape device assembling control method in a multi-host system according to claim 1, wherein the host number of the own host is recorded in the host device assignment information of the host, and information indicating that the magnetic tape device is being assigned by the own host is displayed. . 6. The apparatus releasing means retrieves a record from a global device management table on the inter-host data recording device using the medium name as a key when a release request of the magnetic tape is made using the medium name as a parameter. 3. The control method according to claim 1, wherein the own host number is deleted from the host device allocation information of the searched record. 7. A computer which reads a medium control information recorded at the head of a magnetic tape loaded in a magnetic tape device, and a computer which, when requested to incorporate the magnetic tape device into the host, If the host is the first built-in host, the medium recognizing means reads medium control information from the magnetic tape loaded in the magnetic tape device and records it in the global device management table. A device incorporating means for acquiring medium control information from the device management table, when the magnetic tape device is allocated to another host based on the host device allocation information in the global device management table when a request for allocating a magnetic tape to its own host is made. Waits for the magnetic tape device to be empty, and A device allocating means for recording in the host device allocation information of the global device management table that the magnetic tape device is being allocated by the host when the device is not allocated to another host; Recording a program for functioning as a device release unit for deleting the fact that the magnetic tape device is being allocated by the host from the host device allocation information of the global device management table when a release request is issued. 8. A computer which reads a medium control information recorded at the head of a magnetic tape loaded in a magnetic tape device, and a computer which, when requested to incorporate the magnetic tape device in the host, requests the computer to execute the process. If it is the first built-in host of the magnetic tape device, the medium recognizing means reads the medium control information from the magnetic tape loaded in the magnetic tape device and records it in the corresponding record of the global device management table. If this is not the first built-in host of the tape device, device mounting means for acquiring medium control information from the corresponding record of the global device management table, and the host device of the relevant record of the global device management table when a request for allocating a magnetic tape to its own host The magnetic tape is loaded based on the assignment information. When the magnetic tape device is assigned to another host, the magnetic tape device waits for a space, and when the magnetic tape device is not assigned to another host, the host device of the corresponding record in the global device management table is set. A device allocating unit for recording in the allocation information that the magnetic tape device is being allocated by the host; A recording medium on which a program for functioning as a device release unit for deleting that a magnetic tape device loaded with a tape is being allocated by its own host is recorded.