JPH0323991B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic tape device, and is particularly applicable to a magnetic tape device equipped with an automatic mechanism that automatically selects a magnetic tape (recording medium) from a storage and attaches it to a recording/reproducing section. The present invention relates to an improvement of a magnetic tape device suitable for use in a magnetic tape device.

In recent years, electronic computer systems are processing increasingly large amounts of information. In computer systems that process such large amounts of information, magnetic tape is used as a storage medium because of its low price per unit of information storage capacity. Then, the processing program notifies the operator of the required magnetic tape identification number via the console, and the operator then takes out the magnetic tape with the notified identification number from the storage location and inserts it into the magnetic tape device. (mount).

On the other hand, a virtual storage method has conventionally been adopted as a method for simultaneously improving the speed and capacity of a storage device. This method uses a combination of a small-capacity, high-speed storage device and a large-capacity, low-speed storage device, and accesses the large-capacity, low-speed storage device through the small-capacity, high-speed storage device. Information is exchanged in relatively large units with the high-capacity high-speed storage device, and the central processing unit selects and uses the required information (words) from among the blocks of information. Therefore, when using (accessing) information in the same block many times, it is only necessary to read it from the large-capacity, low-speed storage device, which takes a relatively long time, and then the information is read out for the number of uses (accesses). Since it is only necessary to read from (or write to) a small-capacity, high-speed storage device, it takes much less time than when directly accessing a large-capacity, low-speed storage device.

Therefore, in recent years, large-capacity storage systems that apply this idea to magnetic tape devices and magnetic disk devices have been put into practical use. In this mass storage system, it has become possible to automatically replace the magnetic tape in the magnetic tape device. That is, magnetic tapes are contained in bullet-shaped cartridges and stored in a large number of honeycomb-shaped shelves, and a picker mechanism is used as a transport means to go back and forth between these shelves to take out the cartridges and store them on the shelves. It's profitable. These cartridge storages and the picker mechanism attached thereto constitute a tape storage section. Unlike conventional magnetic tape devices, magnetic tape devices with such a tape storage section do not require operator intervention, so they can contribute to labor savings, increased speed, and improved reliability. becomes expensive.

Therefore, in order to make such expensive equipment widely available, it is necessary that a plurality of independent computer systems can be used in common.

FIG. 1 is a diagram showing an example of the configuration of such a shared system. In the figure, HostCPU1 is the first computer system, HostCPU2 is the second computer system, and MSS is the magnetic storage system that is the core of the mass storage system. It is a tape device. This magnetic tape device has two control devices CN ₁ CN ₂ , and each of the control devices CN ₁ and CN ₁ can be shared by the first and second computer systems HostCPU1 and HostCPU2.
In addition, each control device serves as the tape storage section.
A tape storage section SHELL is used, which is equipped with two sets of picker mechanisms corresponding to CN ₁ and CN ₂ on a 1:1 basis, and a commonly used shelf for storing tapes. Furthermore,
Two _or more tape drives _{D1 , D2 , .} And each tape drive D ₁ , D ₂ ,...
A standby section is provided in which the magnetic tape to be read next is stored and kept on standby so that recording and playback can be performed continuously. Since this shared system has the above configuration, the first computer system HostCPU1 is connected to one of the control devices _CN1
During the period when one tape drive D1 is recording/reproducing on/from a desired magnetic tape, the other computer system HostCPU2 is connected to another tape drive _D2 via the vacant control unit CN2 _. This allows you to record/play back on another magnetic tape, and if all tape drives are in use, you can start using it as soon as one of them becomes available. It can also be kept on standby.

However, the following problems remain in this shared system. In other words, one computer system is recording and reproducing magnetic tape.
If HostCPU1 is stopped due to a failure, etc., and at the same time another computer system, HostCPU2, is on standby for recording and playback using the same tape drive, the system detects that the tape drive has been occupied for a long period of time, which is considered to be unreasonable, and stops the computer system. The computer system HostCPU1 was forced to remove the magnetic tape it was recording/playing from the tape drive and install another standby magnetic tape, but as a result, the failure was resolved and the system was able to resume operation. Computer systems cannot cope with changing magnetic tapes, and end up recording and reproducing data on completely different magnetic tapes.

The purpose of the present invention is to eliminate such problems, and this purpose is to provide a magnetic tape control section connected to a plurality of host devices,
a tape storage unit that is connected to the magnetic tape control unit and stores magnetic tape media on which tape identifier information for identifying individual magnetic tape media is recorded; and a tape storage unit that is selectively taken out and set from the tape storage unit. A magnetic tape device having a plurality of tape drives for recording and reproducing information on and from a tape medium, comprising a buffer memory for storing tape identifier information stored in each of the tape drive units, and a buffer memory for storing tape identifier information stored in each of the tape drive units, and a buffer memory for storing tape identifier information stored in each tape drive unit; a first verification means that is activated when a tape medium is newly stored in the tape drive and compares and verifies the tape identifier information read from the magnetic tape medium and the tape identifier information stored in the buffer memory;
buffer memory writing means for rewriting the contents in the buffer memory with tape identifier information read from the magnetic tape medium when the comparison results in a discrepancy; and identifier information given by a command from a host device. and a second collation means for comparing and collating the identifier information read from the buffer memory, and generating a signal to permit recording and reproducing operation when a match is found as a result of the comparison and collating, and disabling the recording and reproducing operation when there is a discrepancy. The present invention is achieved by a magnetic tape device characterized in that it is equipped with an abnormality processing means for processing permission, and one embodiment thereof will be described in detail below with reference to the drawings.

FIG. 2 is a diagram showing a part of the magnetic tape device according to the present invention. In the figure, CN ₁ is a control device and Dx is a tape drive. The control device CN ₁ can be connected to four channel devices CH ₁ to CH ₄ and for this purpose four channel interface control units CIF ₁ to
CIF ₄ and a channel cross call control unit CCC for selecting one of these channel interface control units CIF ₁ to CIF ₄ . The control device CN ₁ also connects a device interface control section DIF to a tape drive, and a channel interface control section CIF selected from the device interface control section DIF to connect the channel device tape to the device interface control section DIF. Data and transfer control unit that controls data transfer between drives
It is equipped with a microprogram control unit μpu that controls and coordinates all operations of XMIT and control device CN ₁ .

On the other hand, the tape drive Dx has two control devices.
It has two interface control units IF ₁ and IF ₂ for connection to CN ₁ CN ₂ , and a device cross call control unit DCC for selecting one of these two interface control units IF ₁ and IF ₂ . a modulation/demodulation circuit MDM which transmits/receives recording/reproduction information to one interface control unit via the device cross call control unit DCC and modulates/demodulates signals on the magnetic tape; and the modulation/demodulation circuit MDM. An electromagnetic transducer that sends a playback signal to the magnetic tape and performs recording/playback on the magnetic tape using a recording signal from the modulation/demodulation circuit MDM, and controls the mechanical operation of the electromagnetic transducer and the magnetic tape from the selected interface control unit. It is equipped with a tape drive mechanism MECH that operates based on control signals. Furthermore, the tape drive Dx has a buffer memory BUFF, and by this buffer memory BUFF and the microprogram control unit μpu in the control device CN ₁ ,
Although the configuration is based on the present invention, the conceptual configuration of the microprogram control section will be explained next with reference to FIG.

In FIG. 3, CCC is a channel cross call control section, DIF is a device interface control section, and the parts other than these are the essential parts of the microprogram control section μpu.

MAIN is a regular control unit that performs various control operations that are not directly related to the operations according to the present invention, and the regular control unit other than MAIN is a portion that performs control operations regarding the buffer memory BUFF shown in FIG.
The control operations related to buffer memory BUFF are mainly 3.
It is divided into two parts, each of which will be explained in turn.

(i) Rewriting the buffer memory BUFF (performed when the magnetic tape is installed).The load interrupt detection unit LOAD shown in Figure 3 indicates the current control of the tape drive.
When an interrupt indicating that magnetic tape loading is completed occurs in the Dx, the load interrupt reporting unit detects this and reports this to the computer system via the channel cross call control unit CCC.
Start TELL. Also, at this time, the load interrupt detection unit LOAD is connected to the rewrite control flip-flop.
By setting EXCH, the control operation is separated from the regular control section MAIN. It goes without saying that when this operation is realized by a microprogram, it is equivalent to transitioning from a main routine to a subroutine. The rewriting control flip-flop EXCH outputs
The SUBI is subsequently transmitted to the regular control unit MAIN to each unit related to the operation up to the point where control is continued. First, this output SUBI activates the buffer memory read section READB, which causes the buffer memory read section READB in the tape drive Dx to be activated via the device interface control section DIF.
The content of BUFF, CURRENT, is obtained. Second
Then, the output SUBI activates the tape identifier read unit READT, and the identifier NEW is thereby read from the magnetic tape that has been completely installed in the tape drive Dx via the device interface control unit DIF. Third, the information obtained from these buffer memory read section READB and tape identifier read section READT.
CURRENT, NEW is given to the comparative example CMP,
Make a comparison. As a result of this comparison, if an output OKI indicating a match is obtained, the rewrite control flip-flop is immediately transferred via the OR gate CRI.
Since EXCH is reset, control operations are transferred to the regular control unit MAIN. Otherwise, the output OKI from the comparator CMP indicates a mismatch between the two, and by inverting this output OKI by the inverting gate IN,
An active output "1" is obtained. and,
This output “1” and the rewriting control flip-flop
The AND gate section AND detects that both EXCH outputs are active,
Start the buffer memory write section WRITEB.
As a result, the information (identifier) from the tape identifier read unit READT is stored in the buffer memory BUFF of the tape drive Dx via the device interface control unit DIF, and then the rewrite control is performed via the OR gate OKI by the rewrite end output ENDI. Flipflop EXCH is reset,
Shift to the control operation of the regular control unit MAIN.

(ii) Resetting the buffer memory BUFF (performed when removing the magnetic tape) Regular control unit MAIN
performs magnetic tape control over the tape drive Dx by a command from the computer system or by detecting that another computer system is on standby due to exclusive use of a particular tape drive for an unequal amount of time. remove the parts. When the tape drive Dx notifies the end of this unloading operation by an interrupt, the unload interrupt detection unit UNLOAD detects this and activates the buffer memory set unit WRITEB'. As a result, the buffer memory reset section
WRITEB′ is the device interface control section
The buffer memory BUFF of the tape drive Dx is reset via DIF. For example, this reset is performed by writing special contents to the buffer memory BUFF, and the buffer memory BUFF is reset.
The contents of BUFF now indicate that it is not an identifier for any magnetic tape. After that, the control operation is performed by the regular control unit MAIN.

(iii) Identifier verification (performed when a verification instruction command is received) In the present invention, the magnetic tape identifier is the one expected by the computer system and the one of the magnetic tape actually installed in the tape drive. This operation is performed in response to a request from the computer system. In other words, a computer system that has this requirement, for example, a computer system that is about to restart operation after recovery from a failure, will respond to a command chain consisting of a series of recording and playback commands.
A collation command can be added to the beginning part. The verification instruction command is accompanied by the magnetic tape identifier expected by the computer system as reference information. On the other hand, in the control device CN ₁ that received this verification instruction command and its reference identifier, the verification command detection unit
VFYCMD detects this command, sets the verification control flip-flop VFY, and separates the control operation from the regular control unit MAIN in the same manner as in the case (i) above. Further, the output SUB of the rewriting control flip-flop VFY is transmitted to each section operating during the period when the collation control flip-flop VFY is set. 1st
In this case, this output SUB activates the buffer memory read section READB', and the tape drive is read via the device interface control section DIF.
Contents of buffer memory BUFF in Dx
CURRENT is acquired. Second, the reference identifier given together with the verification instruction command.
The comparison unit compares the contents of the reference identifier storage unit REG that stores Ref with the contents of the buffer memory acquired by the buffer memory read unit READB′.
This is done in CMP′. As a result of this comparison, if the two match, the output of the comparison section is OK.
becomes "1" and resets the verification control flip-flop via the OR gate section OR. In other words, since the magnetic tape is installed in the tape drive as expected by the computer system, it is possible to permit a series of instructions following this collation instruction instruction, and therefore, a regular user who executes these series of instructions can The control operation is taken over by the control unit MAIN. On the other hand, depending on the comparison result in the comparison section CMP', both Ref and CURRENT
If it is determined that there is a mismatch, the comparison section
Since the output OK of CMP' becomes "0" and the output after passing through the inversion gate IN' becomes "1", the abnormality processing section receives the output "1" of the inversion gate IN'.
ERROR is triggered. When the error processing unit ERROR is activated, the buffer memory read unit
The content CURRENT from READB' is edited during the reporting status to the computer system, and the series of commands following the verification instruction command are invalidated. Then, information indicating that a match cannot be found is sent to the computer system. As a result,
When the verification control is completed and the end output END resets the verification control flip-flop VFY via the OR gate section OR, the regular control section MAIN transmits the edited status to the computer system in response to a status check command given from the computer system. Transfer to.

As explained above in accordance with the embodiments, in the present invention, when a computer system recovers from a failure and restarts operation, the contents stored in the buffer memory, that is, the contents loaded in the tape drive, can be retrieved by executing a verification command. Since it is possible to check whether the magnetic tape identifier in use matches the magnetic tape identifier expected by the computer system, destruction of unnecessary information on the magnetic tape can be prevented. However, since the magnetic tape is immediately read out from the buffer memory and checked without any mechanical action such as rewinding and rereading the magnetic tape, smooth control can be performed with almost no time loss.

In the embodiments described above, the contents of the microprogram control unit μpu have been shown by a circuit, but it goes without saying that something equivalent to this can be constructed by the microprogram itself. Furthermore, the present invention can be applied to a case where three or more computer systems share a magnetic tape device, and the same effect can be obtained. Also, in magnetic tape devices where the operator intervenes to load the magnetic tape,
The present invention can be similarly applied to prevent operational errors.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a shared configuration of a conventional large-capacity storage system, FIG. 2 is a diagram showing a configuration of a magnetic tape device to which the present invention is applied, and FIG. FIG. 2 is a diagram showing a conceptual configuration example. BUFF...Buffer memory, READB...Buffer memory read section, WRITEB...Buffer memory write section, REC...Reference identifier storage section,
CMP′...Comparison section, ERROR...Error processing section.

Claims (1)

[Scope of Claims] 1. A magnetic tape control unit connected to a plurality of host devices, and a magnetic tape medium connected to the magnetic tape control unit and recording tape identifier information for identifying individual magnetic tape media. A magnetic tape device comprising: a tape storage section for storing tape media; and a plurality of tape drives for recording and reproducing information on tape media selectively taken out and set from the tape storage section, wherein each tape drive section a buffer memory for storing tape identifier information stored in the magnetic tape medium; the buffer memory is activated when a magnetic tape medium is newly stored in the tape drive in the magnetic tape control unit, and the buffer memory stores the tape identifier information read from the magnetic tape medium; a first collation means for comparing and collating the tape identifier information stored in the buffer memory;
buffer memory writing means for rewriting the contents in the buffer memory with tape identifier information read from the magnetic tape medium when the comparison results in a discrepancy; and identifier information given by a command from a host device. and a second collation means for comparing and collating the identifier information read from the buffer memory, and generating a signal to permit recording and reproducing operation when a match is found as a result of the comparison and collating, and disabling the recording and reproducing operation when there is a discrepancy. What is claimed is: 1. A magnetic tape device comprising: abnormality processing means for determining permission.