JPH07122953B2 - Secondary storage access method - Google Patents

Description

The present invention relates to an access method of 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]

The secondary storage device in a computer system usually includes a control device and one or more drive devices connected thereto. In particular, when the recording medium is a replaceable medium, there is a secondary storage device having a plurality of media built-in with an automatic medium exchange device.
The controller is connected to the host, receives commands from the host regarding the operations to be performed, addresses on the medium (data transfer start position), length (data transfer length), etc., and after converting this command information into the necessary order information. , Controls data transfer between 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 writes the data transferred from the control device to the recording electric body. The automatic media conversion device receives order information regarding medium movement from the control device, mounts the specified medium from the medium storage position to the drive position, and demounts the specified medium from the drive device to the medium storage position. To another medium storage position.

[Problems to be solved by the invention]

In the computer system, the secondary storage device itself generally manages the medium stored in the automatic medium conversion device, and the host recognizes the medium currently mounted in the drive device as the address space accessed in the past. However, it does not recognize the entire address space of the medium. Conventionally, in such a system, when the host accesses the secondary storage device, the host specifies the device number of the drive device by a real number which is a fixed number for the drive device. Therefore, for example, the following problems have occurred.

When the host wants to access a certain address space A of a medium, the controller is instructed to access the address space A. At this time, the device number a of the drive device on which the corresponding medium is to be mounted is designated. The control device that received the command,
The corresponding medium is mounted on the corresponding drive device a by the automatic medium exchange device, and the address space A is accessed. Then, when the host needs to access another address space B included in the medium, the host does not recognize that A and B are included in the same medium. Further, since the mounted address space A is generally highly likely to be subsequently accessed, it is desired to mount the address space A on the drive device a as it is. Therefore, the control device is instructed to mount the medium having the address space B on another drive device b and access the address space B.

In such a case, the controller must demount the media from drive a and mount it on drive b. Generally, it takes dozens of seconds until the medium is demounted and mounted, so that the host access to the address space B is significantly delayed. Further, in this case, the address space A in which the host recognizes that it is mounted in the drive device a
Has been demounted from the drive device a.
Since the host cannot recognize it, the next address space A
Access to the drive device a is specified.

As described above, when the device number of the drive device designated by the host is a real number fixed to the drive device, an operation of simply moving between the drive devices with respect to one medium frequently occurs, and the entire system is It causes a significant decrease in performance.

Even if the host has a function of recognizing the entire address space of the medium currently mounted on the drive device by its own command, in a multi-host system in which a large number of hosts are connected, one host is When mounted, other hosts cannot see the entire address space of the mounted medium as well as that host. In addition, if another host tries to recognize the entire address space of the medium currently mounted in the drive device before accessing, special processing such as referencing the mount state to the secondary storage device is necessary. However, the system becomes complicated and the processing capacity is lowered.

An object of the present invention is to provide a computer system in which a secondary storage device containing a plurality of removable recording media is connected to a host.
Even if the host does not recognize the address space of the medium mounted on the drive device in the next storage device, it is possible to quickly access any address space without degrading the performance.

[Means and Actions for Solving Problems]

According to the present invention, the device numbers of a plurality of drive devices are defined by 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 the drive device is mounted on the secondary storage device side. Means for storing the address space of the medium, the virtual number and the real number of the drive, the means for assigning the virtual number of the drive to the real number, and the medium requested by the host is the drive. Means for determining whether or not the medium is mounted on the medium, a means for storing both the address space of the medium in the automatic medium changing device and the address of the medium storing position for storing the medium, and the medium requested by the host. And means for determining whether the medium is stored in the medium storage position. As a result, when the host accesses the secondary storage device, the device number of the drive device can be specified by a virtual number, and the host address space of the medium mounted on the drive device in the secondary storage device can be specified. Can quickly access any address space without needing to recognize it one by one.

〔Example〕

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

FIG. 1 is an embodiment of the present invention in which one or more hosts 10 are included.
And a secondary storage device 20 connected thereto. The secondary storage device 20 includes one control device 30, a plurality of drive devices 40, and one automatic medium changing device 50. The automatic medium changing device 50 has a plurality of medium storing positions 60. The control device 30 and the automatic medium changing device 50, and the control device 30 and the plurality of drive devices 40 are connected by a known method. The control device 30 includes a mount table 31, a storage table 32, and a mount determination mechanism 33.
A virtual number determination mechanism 34, a virtual number assignment mechanism 35,
The storage determination mechanism 36 is provided.

FIG. 2 shows a configuration example of the tables 31 and 32 shown in FIG. The structure of the mount table 31 is shown in FIG. 2 (a), which corresponds to a plurality of drive devices 40 and is a drive device real number which is a device number fixed to the drive device and a control device.
30 is a virtual drive number dynamically assigned to the corresponding drive,
A virtual number identification flag that identifies whether a virtual number is assigned to the corresponding drive, a mount identification flag that identifies whether a medium is mounted on the corresponding drive, and an address space of the mounted medium are stored. ing. For example, "0" is stored in the virtual number identification flag if the virtual number is not assigned, and "1" is stored if the virtual number is assigned. In the mount identification flag, for example, "0" if the medium is not mounted, "1" if the medium is mounted
I remember. The structure of the storage table 32 is shown in FIG. 2 (b), which corresponds to each of the plurality of medium storage positions 60.
The medium storage position address, the storage identification flag for identifying whether or not the medium is stored in the medium storage position, and the address space of the stored medium are stored. The storage identification flag is, for example, "1" when the medium is stored, and is "0" when the medium is not stored.
Memorize

The mount determination mechanism 33 of the control device 30 is
This is a mechanism for determining the medium mounted states of the plurality of drive devices 40 with reference to 31. The virtual number determination mechanism 34 is a mechanism that refers to the mount table 31 and determines the virtual number allocation state of the plurality of drive devices 40. The virtual number assignment mechanism 35
This is a mechanism for allocating the virtual number of the drive unit 40 requested by the host 10 to the real number. The storage judgment device 36 is a storage table.
This is a mechanism for determining the medium storage state of a plurality of medium storage positions 60 with reference to 32. The substance of the control device 30 is, for example, a microprocessor, and the respective mechanisms 33 to 36 are provided, for example, as program subroutines.

FIG. 3 is a host in the secondary storage device 20 shown in FIG.
Normal media access operation from 10 (eg read,
Write operation) flow, and the medium access operation in the secondary storage device 20 will be described below with reference to FIG. In FIG. 3, A is a host, B is a control device, C is a drive device, and D is an automatic medium changing device.

First, when the host 10 requests a medium access, in step 100, the host 10 uses a known method such as a file name specified by an operator or a program to determine an address and a length at which the file is stored or should be stored. Derive. The host 10 converts the derived address and length, an appropriate virtual number of the driving device 40 to be mounted, required operation, and other information into command information, and in step 101, the control device 30
Send to.

In step 102, the control device 30 refers to the mount table 31 by the mount determination mechanism 33 to determine whether the medium having the requested address and the address range for the length is mounted in any of the plurality of drive devices 40. Find out. As a result of checking in step 102, if the corresponding medium is mounted, the control device 30 causes the virtual number determination mechanism 34 to similarly mount the mount table 31 in step 103.
Referring to, check whether the virtual number of the drive unit 40 requested to be mounted by the host 10 matches the virtual number assigned immediately before the drive unit 40 mounting the corresponding medium. . As a 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 determines in step 104.
Then, the address and length of the medium, the required operation, and other information are converted into order information and sent to the drive device 40 mounting the medium. Thereafter, the controller 30 controls the operation requested by the host in step 105 by a known method.

As a result of checking in step 103, if the virtual number in the current access and the virtual number assigned immediately before do not match, the control device 30 determines in step 106 that the real number of the corresponding drive device 40 in the mount table 31. The virtual number in the current access is stored in the corresponding virtual number column, and the process proceeds 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,
In step 107, the control device 30 refers to the storage table 32 by the storage determination mechanism 36 to check in which of the medium storage positions 60 the medium is stored. If the corresponding medium is not stored in any of the medium storing positions 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, the corresponding medium is at the medium storage position 60.
If stored in one of the
At 109, the virtual number determination mechanism 34 checks whether or not the virtual number of the drive device 40 requested by the host 10 exists in the virtual number column of the mount table 31. As a result of checking in step 109, if the virtual number is present, the control device 30 uses the mount determination mechanism 33 in step 110, and another medium other than that requested by the host 10 to the drive device 40 to which the virtual number is assigned. Check if is mounted. As a result of checking in step 110, if another medium is not mounted in the drive device, the control device 30 causes the storage determination mechanism 36 to determine the medium storage position 60 storing the medium requested by the host 10 in step 111. Identify. In step 112, the control device 30 mounts the medium stored in the specified corresponding medium storage position 60 on the corresponding drive device 40 so as to display the medium storage position address, the real number of the mount drive device, the mount operation, and other information. It is converted into command information and sent to the automatic media changing device 50.

In step 113, the automatic medium changing device 50 takes out the medium from the medium storing position 60 requested by the control device 30 and mounts it on the required driving device 40. When the mount operation is completed, the automatic media changing device 50 proceeds to step 114 to control device 30.
Report the completion of mounting. The control device 30 executes step 115.
Then, when the mount identification flag corresponding to the drive device 40 of the mount table 31 is set to "1", the necessary processing associated with the medium mounting 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 column of the mount table 31, the control device 30 mounts the medium by the mount determination mechanism 33 in step 116. Check if there is an idle drive not present. As a result of checking in step 116, if an idle driving device is present, the control device 30 selects one driving device 40 from the idle driving 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 drive device 40 selected in the mount table 31, and at the same time sets the corresponding virtual number identification flag to “1”. To do. Then, the process goes to step 111 to mount the medium requested by the host 10 on the corresponding drive device 40.

If the idle drive is not present as determined by step 116, the controller 30 selects the drive 40 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 column corresponding to the drive device 40 selected in the mount table 31. In step 121, the control device 30 uses the storage determination mechanism 36 to identify the medium storage position 60 in which the medium to be demounted is stored. In step 122, the control device 30 stores the medium storage position address, the actual number of the demount drive device, the demount operation, and other information so that the medium is demounted from the corresponding drive device 40 and stored in the specified medium storage position 60. It is converted into command information and sent to the automatic media conversion device 50.

In step 123, the automatic media conversion device 50 demounts the medium from the requested drive device 40 and stores it in the requested automatic media exchange device 60. When the demount operation is completed, the automatic medium changing device 50 reports the demant completion to the control device 30 in step 124. In step 125, the control device 30 sets the mount identification flag corresponding to the drive device 40 of the mount table 31 to "0", and also performs the necessary processing associated with the medium demounting. Thereafter, the process goes to step 111 to mount the medium requested by the host 10 on the drive device 40.

As a result of checking in step 110, if another medium other than the one requested by the host 10 is mounted on the drive device 40 to which the corresponding virtual number is assigned, the control device 30 proceeds to step 126.
Then, the mount determination mechanism 33 checks whether or not there is an idle drive device that does not mount the medium. Step
As a result of checking in 126, if there is an idle drive device, the procedure goes to step 117. As a result of checking in step 126, if there is no empty drive, the process goes to step 121 to demount the medium mounted in the drive 40 assigned the virtual number.

The above is the operation flow of the secondary storage device 20 in the normal operation. When the host wants to specify and access the drive device 40, the real number of the drive device may be designated. For this purpose, the control device 30 includes a recognition means for recognizing whether the device number of the drive device designated by the host is a real number or a virtual number. Alternatively, two operation modes may be pre-arranged in the system depending on whether the device number designated by the host is a real number or a virtual number. For example, which operation mode is set in the control device 30 as appropriate. Means of saving are included.

As described above, in the present embodiment, the control device 30 includes the storage table 32 and the storage determination mechanism 36, and manages up to the storage position of the medium.
The storage automatic storage device 50 may be provided with a storage determination mechanism 36, and the storage position of the medium may be managed by the automatic medium exchange device 50. In this case, the medium storage address specifying operation in the operation flow of FIG. 3 is performed by the automatic medium exchange apparatus 50, not by the control apparatus 30. Further, after the order transfer from the control device 30 to the automatic medium exchange device 50, the medium storage address specifying operation is performed. As described above, the device including the storage table 32 and the storage determination mechanism 36 and the operation flow described above are merely examples, and can be arbitrarily designed according to the specific implementation method of the present invention. .

Further, although the present embodiment has been described with respect to the secondary storage device having one control device and one automatic media exchange device, the secondary storage device having a plurality of control devices and a plurality of automatic media exchange devices is also described. It is easily understood that the same method as that of this embodiment is used.

〔The invention's effect〕

As described above, according to the present invention, a virtual number is given to a drive unit, and a host can access by the virtual number, so that the medium mounted on the drive unit in the secondary storage device can be Even if the host does not recognize the address space one by one, there is an advantage that any address space can be quickly accessed without degrading the performance.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing a configuration example of the tables in FIG. 1, and FIG. 3 is a diagram showing an operation flow example during normal operation of FIG. Is. 10 ... Host, 20 ... Secondary storage device, 30 ... Control device,
31 …… Mount table, 32 …… Storage table, 33 ……
Mount determination mechanism, 34 ... Virtual number determination mechanism, 35 ... Virtual number assignment mechanism, 36 ... Storage determination mechanism, 40 ... Drive device, 50 ... Automatic medium exchange device, 60 ... Medium storage position.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyoshi Izawa 3-9-11 Midoricho, Musashino-shi, Tokyo Inside Nippon Telegraph and Telephone Corporation Electronic Mechanical Engineering Laboratory (72) Inventor Tatsuda Takeshi Midori-cho, Musashino-shi, Tokyo 9-11 Nippon Telegraph and Telephone Corporation, Research Institute of Electronic Mechanism (72) Inventor Katsuhiro Kurosawa 4-3-1, Tsunashima-higashi, Kohoku-ku, Yokohama-shi, Kanagawa Matsushita Communication Industrial Co., Ltd. (72) Inventor Shin Watanabe Kanagawa 4-3-1, Tsunashimahigashi, Kohoku-ku, Yokohama Matsushita Communication Industrial Co., Ltd. (72) Inventor Takashi Oka 2880 Kozu, Odawara City, Kanagawa Hitachi Ltd. Odawara Factory (72) Inventor Taka Doi Odawara, Kanagawa 2880, Kozu, Ichi, Japan Otawara Plant, Hitachi Ltd.

Claims (1)

[Claims] 1. A secondary storage device having a removable recording medium is connected to a central processing unit, the secondary storage device being a control unit connected to the central processing unit, and a plurality of drives connected to the control unit. In a computer system consisting of a device and an automatic medium exchange device including a plurality of medium storage positions, both a real number in which the device numbers of the plurality of drive devices are fixed to the drive device and a virtual number which is the same as or different from the real number And a means for storing, on the secondary storage device side, the address space of the exchangeable recording medium mounted on the drive device, the virtual number of the drive device, and the real number. Means for dynamically assigning the virtual number of the drive unit to the real number of the drive unit, and determining whether or not an exchangeable recording medium requested by the central processing unit is mounted in the drive unit Means and Means for storing both the address space of the removable recording medium in the medium automatic exchange device and the address of the medium storing position for storing the medium, and the removable recording medium requested by the central processing unit is the medium. A means for judging whether or not the drive is stored in the storage position is provided, and the central processing unit specifies the device number of the drive unit by a virtual number when accessing the secondary storage device.
Next storage access method.