JPS62267965A - Accessing system for secondary storage device - Google Patents

Abstract

PURPOSE:To rapidly enable an optional address space to be accessed without lowering a capacity even when the address space of a medium mounted at a driving device in a secondary storage device is not recognized one by one by a host, by adding a virtual number of the driving device, and enabling the host to access by the virtual number. CONSTITUTION:When a request to make an access to the medium by a host 10 is generated, an address, and a length to be stored are derived from a file name, etc., designated by a program, and the appropriate virtual number, an operation to be required, bits of other information of a driving device 40 are converted to bits of command information, and they are sent to a control device 30. The control device 30 refers to a mount table 31 by a mount judging mechanism 33, and investigates on which control device 30 out of plural control devices the bit of information is mounted. Also, it refers to the mount table 31 similarly by a virtual number judging mechanism 34, and investigates whether the virtual number of the driving device 40 coincides with the virtual number allocated just before. When they coincide, the bit of information is converted to a bit of order information, and it is sent to the driving device 40 on which a corresponding medium is mounted.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an access method for a secondary storage device in a computer system in which a secondary storage device having a removable recording medium is connected to a central processing unit (host). .

[Conventional technology]

A secondary storage device in a computer system typically includes a control device and one or more drive devices connected to the control device. Particularly when the recording medium is a removable medium, there are secondary storage devices with built-in multiple media and an automatic medium exchange device.

The control device is connected to the host, and is able to control the operation to be performed, the address on the medium (data transfer start position), and the length (
Receives commands regarding data transfer length etc. from the host.

After converting this command information into the necessary ordering information, it controls data transfer between the appropriate drives and other system elements. The drive device operates the mounted recording medium, reads data from the recording medium, transfers the data to the control device, and also writes the data transferred from the control device to the recording medium. The automatic media exchange device receives order information regarding media movement from the control device,
Mounting the specified medium from the medium storage position to the drive device, and demounting the specified medium from the drive device to the medium storage position,
Furthermore, it is moved from one medium storage position to another medium storage position.

[Problem that the invention seeks to solve]

In computer systems, the secondary storage device itself generally manages the media stored in the automatic media switching device, and the host recognizes the media currently mounted on the drive device as an address space accessed in the past. Conventionally, in such systems, when a host accesses a secondary storage device, the host fixes the device number of the drive device to the drive device. It was specified by a real number.

Therefore, for example, the following problems have arisen.

When a host wants to access address space A on a certain medium, it instructs the control device to access address space A. At this time, the device number a of the drive device on which the corresponding medium is to be mounted is specified.

Upon receiving the command, the control device causes the automatic medium exchange device to mount the corresponding medium in the corresponding drive device la, and accesses the address space A. Next time the host needs to access another address space B contained in the medium, the host does not recognize that A and B are contained in the same medium. Further, since the mounted address space A is generally likely to be accessed continuously, it is assumed that address space A is desired to be mounted on the N drive device a as it is. Therefore, the control device is instructed to mount the medium having address space B on another drive device and access address space B.

In such a case, the control device must demount the medium from drive device a and mount it in drive device A. Generally, it takes several seconds to demount and mount a medium, which significantly slows host access to address space B.

Further, in this case, the address space A that the host recognizes as being mounted on the drive device a has been demounted from the drive device 1a.

Since the host cannot recognize it, the primary address space A
access specifies drive device a.

In this way, if the device number of the drive device specified by the host is a real number fixed to the drive device, operations such as simply moving one medium between drive devices frequently occur, and the entire system becomes This will cause a significant drop in performance.

Even if the host has the ability to recognize the entire address space of the media currently mounted on the drive device by its own command, in a multi-host system with many hosts connected, one host may When mounted, other hosts do not see the entire address space of the mounted medium in the same way as the host itself. Additionally, if another host wishes to recognize the entire address space of the medium currently mounted on the drive device before accessing it, special processing such as referencing the mounting status of the secondary storage device is required. , leading to system complexity and reduced processing capacity.

An object of the present invention is to provide a computer system in which a secondary storage device including a plurality of removable recording media is connected to a host.
To enable quick access to any address space without deteriorating performance even if a host does not recognize the address space of a medium mounted on a drive device in a storage device one by one.

[Means and effects for solving the problem] The present invention defines the device numbers of a plurality of drive devices as both a real number fixed to the corresponding drive device and a virtual number that is the same as or different from the corresponding real number, and 2. Next, on the storage device side, means for storing the address space of the medium mounted on the drive device, the corresponding virtual number and the corresponding real number of the corresponding drive device, and means for assigning the virtual number of the drive device to the real number. , a means for determining whether or not a medium requested by a host is mounted on a drive device, and a means for storing both the address space of the medium in the automatic medium exchange device and the address of the medium storage location where the medium is stored. and means for determining whether the medium requested by the host is stored in the medium storage location. As a result, when the host accesses the secondary storage device, it becomes possible to specify the device number of the drive device with a virtual number, and the address space of the media mounted on the drive device in the secondary storage device can be specified by the host. This means that any address space can be quickly accessed without having to recognize it one by one.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the invention in which one or more hosts 1
0 and a secondary storage device 20 connected to it. The secondary storage device 20 includes one control device 30 and a plurality of drive devices 4
0.1 medium automatic exchange device 50 is included. The automatic media exchange device 50 has a plurality of media storage locations 60. The control device 30 and the automatic medium exchange device 50, and the control device 30 and the plurality of drive devices 40 are each connected by a known method. The control device 30 includes a mount table 31, a storage table 32, a mount judgment mechanism 33, a virtual number judgment mechanism 34, a virtual number allocation mechanism 35, and a storage judgment mechanism 3.
6.

FIG. 2 shows an example of the configuration of the tables 31 and 32 in FIG. 1. In FIG. 2(a), a mount table 31 is shown.
A drive device real number, which is a device number fixed to the corresponding drive device, corresponds to a plurality of drive devices 40;
control! ! A drive device virtual number that is dynamically assigned to the drive device by the drive device 30, a virtual number identification flag that identifies whether a virtual number is assigned to the drive device, and a virtual number identification flag that identifies whether or not a virtual number is assigned to the drive device. A mount identification flag for identification and an address space of the mounted medium are stored. For example, if a virtual number has not been assigned, "110" is stored in the virtual number identification flag, and if a virtual number has been assigned, "1" is stored.

The mount identification flag stores, for example, "0" if the medium is not mounted, and "1" if it is mounted. FIG. 2(b) shows the configuration of the storage table 32, in which multiple media Corresponding to each storage position 60, a corresponding medium storage position address, a storage identification flag for identifying whether or not a medium is stored in the corresponding medium storage position, and an address space of the stored medium are stored. The storage identification flag stores, for example, ``1'''' when a medium is stored, and 0'' when no medium is stored.

The mount determination mechanism 33 of the control device 30 is a mechanism that determines the medium mounting state of the plurality of drive devices 40 by referring to the mount checker 31. The virtual number determination mechanism 34 is
The virtual number assignment of the plurality of drive devices 4o with reference to the mount table 31 is a mechanism for determining the state. The virtual number allocation mechanism 35 assigns the drive device 4 requested by the host 10
This is a mechanism that assigns a virtual number of 0 to a real number. Storage judgment 4i! 36 is a mechanism that refers to the storage table 32 and determines the media storage status of the plurality of media storage locations 60. The substance of the control device 30 is, for example, a microprocessor,
Each of the mechanisms 33 to 36 is provided, for example, as a subroutine of a program.

FIG. 3 is a flowchart of operations (for example, read and write operations) during normal medium access from the host 1o in the secondary storage device 20 shown in FIG. The media access operation will be explained. In FIG. 3, A indicates a host, B a control device, C a drive device, and D an automatic medium exchange device.

First, when the host 10 requests medium access,
In step 100, the host 10 derives the address and length at which the file is stored or to be stored from the file name specified by the operator or the program by a known method. The host 10 is
The derived address and length, the appropriate virtual number of the drive device 40 to be mounted, the required operation,
Convert other information to command information, step 101
and sends it to the control device 30.

control] [30 is the mount judgment mechanism 33 in step 102
By referring to the mount table 31, it is determined whether a medium having the address range for the requested address and length is mounted on any of the plurality of drive devices 40. As a result of checking in step 102,
If the corresponding medium has been mounted, the control table [30 in step 1o3 uses the virtual number determining mechanism 34 to also refer to the mount table 31 and determines the virtual number of the drive device 40 requested to be mounted by the host 10. It is checked whether the virtual number matches the virtual number assigned immediately before the drive device 40 that mounts the medium. The result of checking in step 103.

If the virtual number in the current access matches the virtual number assigned immediately before, the control device 30 converts the address and length of the medium, the required operation, and other information into order information in step 104, and The media is sent to the mounting drive 40. Thereafter, the control device 3o controls the operation requested by the host in step 105 using a known method.

As a result of checking in step 103, if the virtual number in the current access does not match the virtual number assigned immediately before, in step 106, the control device 30 changes the real number of the corresponding drive device 40 in the mount table 31 to The virtual number for the current access is stored in the corresponding virtual number field, and the process goes to step 104.

On the other hand, as a result of checking in step 102, if the desired medium is not mounted on any of the plurality of drive devices 40, the control device 30 controls the storage determination mechanism 36 in step 107.
By referring to the storage file 32, it is checked in which of the medium storage locations 60 the corresponding medium is stored. If the corresponding medium is not stored in any of the medium storage locations 60, the control device 30 notifies the host that the corresponding medium is not stored in step 108, and thereafter waits for an instruction from the host.

As a result of checking in step 107, if the corresponding medium is stored in any of the medium storage locations 60, the control device 30 determines whether the host 1
It is checked whether the virtual number of the drive device 4o requested from 0 exists in the virtual number column of the mount table 31.

As a result of checking in step 109, if a virtual number exists,
Control table [30 is the mount judgment machine 411 at step 110
33 to check whether another medium other than that requested by the host 10 is mounted on the drive device 40 to which the corresponding virtual number is assigned. As a result of checking in step 110, if no other medium is mounted on the corresponding drive device, the control device 130 uses the storage determination mechanism 36 in step 111 to determine the media storage location 60 that stores the medium requested by the host 10. Identify. In step 112, the control device 30 sends the media storage location address, the actual number of the mount drive device, the mounting operation, and other information so that the medium stored in the specified media storage location 60 is mounted on the drive device 40. It is converted into command information and sent to the automatic medium exchange device 50.

In step 113, the automatic medium exchanger 50 performs control '3A.
The medium is removed from the requested media storage location 60 from the storage location 3o and mounted in the requested drive bag @40. When the mounting operation is completed, the automatic medium exchange device 50 performs step 1.
At step 14, a mounting completion report is sent to the control device 30. In step 115, the control device 30 sets the mount identification flag corresponding to the corresponding drive device 40 on the mount table 31 to '1.
'', necessary processing associated with mounting the medium is performed. Thereafter, the process goes to step 104 to control the operation requested by the host.

As a result of checking in step 109, if the virtual number of the drive device 40 requested by the host 10 does not exist in the virtual number field of the mount table 31, the control device 30 uses the mount determination mechanism 33 to mount the medium in step 116. Check to see if there are idle drives that are not running.

As a result of checking in step 116, if an idle drive device exists, the control device 30 selects one drive device 40 from among the idle drive devices in step 117. In step 118, the control device 30 stores the virtual number requested by the host 10 in the virtual number column corresponding to the selected drive device 40 in the mount table 31, and sets the corresponding virtual number identification flag to '1''. do.

Thereafter, the process proceeds to step 111 in order to mount the medium requested by the host 10 on the corresponding drive device 40.

If, as determined in step 116, there are no empty drives, controller 30 selects the drive 40 on which to demount the media in step 119 using any suitable known technique. In step 120, the control device 30 stores the virtual number requested by the host 10 in the virtual number field corresponding to the selected drive device 4o in the mount table 31.

In step 121, the control device 30 uses the storage determination mechanism 36 to select the medium storage position 60 for storing the medium to be demounted.
Identify. In order to demount the corresponding medium from the corresponding drive device 40 and store it in the specified corresponding medium storage location 60, the control device 30 inputs the medium storage location address, the real number of the demount drive device, the demount operation, and other information in step 122. It is converted into command information and sent to the automatic medium exchange device 50.

Automatic media exchanger 50 demounts the media from the requested drive 40 and stores it in the requested automatic media exchanger 60 in step 123 . When the demounting operation is completed, the automatic medium exchange device 5° reports demounting completion to the control device 30 in step 124. In step 125, the control device 30 controls the corresponding drive device 4 of the mount table 31.
When the mount identification flag corresponding to 0 is set to "0", necessary processing associated with medium demounting is performed in both cases.

In order to mount the medium requested by the host 10 on the corresponding drive device 40, the process proceeds to step 111.

As a result of checking in step 110, if a different medium other than that requested by the host 10 is mounted on the drive device 40 to which the corresponding virtual number is assigned.

The control device 30 controls the mount determination mechanism 33 in step 126.
Check to see if there is an empty drive device that does not mount a medium. As a result of checking in step 126,
If an empty drive exists, go to step 117. As a result of checking in step 126, if no idle drive device exists, the drive device 40 to which the corresponding virtual number is assigned
In order to demount the medium mounted on the PC, the process goes to step 121.

The above is the operational flow of the secondary storage device 20 in normal operation. Note that when the host wants to specify and access the drive device 40, it suffices to specify the real number of the drive device.

For this purpose, the control device 30 includes means for recognizing whether the device number of the drive device specified by the host is a real number or a virtual number. or.

Depending on whether the device number designated by the host is a real number or a virtual number, two operating modes should be determined in advance within the system, and for example, which operating mode should be set in the control device 30 as appropriate. Includes means.

In this embodiment, it has been described that the control device 30 is equipped with the storage table 32 and the storage judgment mechanism 36 and manages up to the storage position of the medium. 36, and the storage location management of the media may be performed by the automatic media exchange device 50. In this case, the medium storage address specifying operation in the operational flow of FIG. 3 is performed not by the control device 30 but by the automatic medium exchange device 50. Further, the automatic medium exchange device 5 is connected to the control device 30.
After the order is transferred to 0, a medium storage address specifying operation is performed. In this way, storage table 3 mentioned here
2 and the storage determination mechanism 36 and its operation flow are merely examples, and can be arbitrarily designed according to a specific implementation method of the present invention.

Furthermore, although this embodiment has described a secondary storage device having one control device and one automatic medium exchange device, a secondary storage device having a plurality of control devices and a plurality of automatic medium exchange devices has been described.
It is easily understood that the next storage device is also realized by a method similar to that of this embodiment.

〔Effect of the invention〕

As explained above, according to the present invention, a virtual number is assigned to a drive device, and the host can access it using the virtual number. There is an advantage that even if the host does not recognize each address space, it can quickly access any address space without degrading performance.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing an example of the structure of tables in FIG. 1, and FIG. 3 is a diagram showing an example of the operation flow during normal operation of FIG. 1. It is. 10... host, 20... secondary storage device, 30
...Control device, 31...Mount table, 32
...Storage table, 33...Mount judgment mechanism, 34...Virtual number judgment mechanism, 35...Virtual number allocation mechanism, 36...Storage judgment mechanism, 40...Drive device, 50...・Automatic media exchange device. 60...Media storage position. Figure 1 - 1 - Figure 2

Claims (1)

[Claims] (1) A secondary storage device having a replaceable recording medium is connected to a central processing unit, and the secondary storage device is connected to a control device connected to the central processing unit and a plurality of drive devices connected to the control device. In a computer system comprising an automatic media exchange device including a plurality of media storage locations, the device number of the plurality of drive devices is defined as both a real number fixed to the drive device and a virtual number that is the same as or different from the real number. means for storing, in the secondary storage device, an address space of a removable recording medium mounted on the drive device, the virtual number and the real number of the drive device; means for dynamically assigning the virtual number of a device to the real number of the drive device; and means for determining whether a removable recording medium requested by the central processing unit is mounted on the drive device. , means for storing both an address space of a removable recording medium in the automatic medium exchange device and an address of the medium storage location in which the medium is stored; means for determining whether or not the medium is stored in the medium storage location, and the central processing unit specifies the device number of the drive device using a virtual number when accessing the secondary storage device. Next storage access method.