JPH04285783A - Management method for magnetic tape storage devices - Google Patents

Abstract

PURPOSE:To improve the reliability of an access by recording the same management at serveral positions of a magnetic tape and reading-in the management information located at another position when the management information at a preliminarily specified position can not be read correctly. CONSTITUTION:A management information recording means 2 recording the management information at several positions A, A2 and A3 of a magnetic tape 1 is provided. A management information read-out means 3 is provided which reads out the management information recorded at the preliminarily specified position on the magnetic tape 1, developes them in a memory within the device, and reads out the management information located at the other positions A2 or A3 when the management information located at the position A can not be read correctly. Thus, even when the management information is failed to read correctly due to the deterioration of the normally used first control block of a magnetic tape 1, the management information at the other position can be read-in. Thus, the reliability of the access can be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a management method for a magnetic tape storage device that manages access by reading management information recorded on the magnetic tape itself into the device. When recording management information regarding media and data files on magnetic tape and managing access on a media-by-media basis based on this management information,
If the management information recorded on the magnetic tape cannot be read properly, access control becomes impossible, and improvements in this respect are desired.

0002

[Prior Art] In a conventional magnetic tape storage device,
No information was recorded regarding the presence or absence of any media abnormalities on the magnetic tape or the recorded data files. Therefore, in order to perform appropriate access management according to the state of the magnetic tape, the inventors of the present application have placed a control block in an area different from the user area of the magnetic tape, for example, in the area before the user area at the beginning of the magnetic tape. is set up to record the management information of the magnetic tape, read the management information when loading the magnetic tape, deploy it to the device's internal memory, and perform appropriate access management according to the management information of the magnetic tape in response to access commands from the host. We are proposing a method to do this.

0003

[Problem to be Solved by the Invention] However, in such an access control method that uses management information recorded on a magnetic tape, the management information is recorded all at one place, such as at the beginning of the magnetic tape. Therefore, if the leading part, which is accessed frequently, deteriorates, the management information written in the control block becomes unreadable, causing a problem in which media management and file access management cannot be performed normally.

The present invention has been made in view of these conventional problems, and provides a magnetic tape storage device that allows normal management of media and files even if management information is lost due to deterioration of the media. The purpose is to provide a management method.

[0005]

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention. First, the present invention is a magnetic tape storage device that records management information regarding the medium on the magnetic tape 1, reads the management information when the magnetic tape 1 is loaded, expands it within the device, and manages access for each medium based on this management information. Targets device management methods.

Regarding the management system of such a magnetic tape storage device, the present invention includes a management information recording means 2 for recording management information in a plurality of locations A, A2, and A3 on the magnetic tape 1; The management information recorded in a predetermined specific location A is read out and developed into the memory in the device. If the management information in the specific location A cannot be read normally, the management information in other locations A2 and A3 is read out. The present invention is characterized in that it is provided with management information reading means 3 for reading out management information.

[0007] Here, the management information recording means 2 records flag information L indicating that the management information has been updated when recording the management information on the magnetic tape, and also records the flag information L indicating that the management information has been updated.
When the management information is read from the magnetic tape 1, it is determined from the flag information whether or not it has been updated, and if it is confirmed that it has been updated, it performs corresponding processing such as prohibiting access. Furthermore, the management information recording means 2 records a first position (control block) A between the physical tape start position (physical BOT) at the head of the magnetic tape 1 and the logical start position (logical BOT) of the user data area. For the user area, management information is recorded in the second position A2 following the write end position of the data file, and in the second position A2 before the physical tape final position (physical EOT) of the magnetic tape. 3. Record management information in position A3.

[0008] Furthermore, the management information recording means 2 records the management information at the second position A2 following the writing end position of the data file, and when writing new data, the management information at the second position A2 is recorded. After writing a new data file overlapping the information, management information is recorded at a second position A2' following the final position of the new data file. Furthermore, when the management information recording means 2 receives an unload command from the host device,
The management information developed in the device is updated by overwriting a plurality of pieces of management information already recorded on the magnetic tape.

On the other hand, as management information to be recorded on the magnetic tape 1, medium management information for the magnetic tape itself and file management information for user data recorded on the magnetic tape are created and recorded. Specifically, as media management information, the media number, presence or absence of media abnormality, and number of times the media has been used are recorded, and as file management information, physical location information of the data file (physical block ID indicating the tape mark) is recorded. ) and logical position information (logical block ID indicating tape mark)
) is recorded.

0010

[Operation] According to the management method of the magnetic tape storage device of the present invention having such a configuration, since the same management information is recorded in multiple locations on the magnetic tape, for example, the management information at the beginning of the magnetic tape that is constantly used is Even if the control block deteriorates and the management information cannot be read normally, the management information recorded after the last data file in the user area and even at the end of the tape can be read normally. It is possible to reliably prevent data from being lost from the magnetic tape and becoming unmanageable.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a block diagram showing an embodiment of a magnetic tape storage device to which the management system of the present invention is applied. In FIG. 2, the magnetic tape storage device of the present invention is roughly divided into a magnetic tape storage control device 10 and a magnetic tape drive device 12.

The magnetic tape drive device 12 is provided with a drive controller 32 and a drive 34, and performs loading, writing, reading, and unloading operations on the magnetic tape according to commands from the magnetic tape storage control device 10. The magnetic tape storage control device 10 analyzes and processes commands and data received from the host computer, and controls the magnetic tape drive device 12.

The magnetic tape storage control device 10 is provided with a microprocessor (MPU) 14, which centrally controls the entire control device. The host interface 16 performs communication with the host computer, and the drive interface 18 performs communication with the magnetic tape drive device 12. The data buffer 20 is used for data transfer associated with writing or reading magnetic tape.
Data transfer of the data buffer 20 is directly managed by the DMA controller 22.

Reference numeral 26 denotes a dip switch, which represents the hardware version number in 4 bytes, and is set at the time of factory shipment. Furthermore, 28 is a control bus, and 30 is a DMA bus. FIG. 3 is an explanatory diagram of the format of the magnetic tape used in the present invention. In FIG. 3, the magnetic tape 1 is housed in a cassette case equipped with a delivery reel 36 and a take-up reel 38, and by setting it in the device, the magnetic tape 1 is pulled out of the case and loaded into contact with the head. . This magnetic tape 1 has a format configuration shown expanded on the bottom.

First, a control block 40 is provided between the physical BOT at the beginning of the magnetic tape 1 and the logical BOT as a recording area in a format different from that for user data. Management information A including file management information of user data recorded in is recorded. The details of this management information A are as follows: (
1) The number of the medium (2) Information indicating whether there is an abnormality in the medium (3) At least the number of times it has been used is recorded.

[0016]Furthermore, as the file management information for user data, for example, a physical block ID indicating the physical position of a tape mark recorded for each file with one data file as one unit, and a physical block ID used for file access from the host side. The correspondence relationship between the logical block IDs of the tape marks to be recorded is recorded. Here, one data file as user data is usually composed of a plurality of data blocks, and the physical position of each data block on the magnetic tape is a control track 46 recorded in parallel with the storage area of the magnetic tape 1. You can know by

That is, the control track 46 records a value that increases by one every predetermined distance from the physical BOT, and by reading this control track 46, the user data, that is, the physical information of each data block constituting the data file is recorded. Able to recognize target position. Furthermore, a tape mark 48 is recorded at the end of a data file to indicate the final position of one data file, and therefore the physical position of the tape mark 48, that is, the physical block ID, and the logical position of the tape mark, that is, Once the correspondence between the logical block IDs is known, the magnetic tape can be directly positioned on the head using the physical block ID of the tape mark that corresponds to the logical block ID instructed by the host.

Furthermore, in the present invention, at the same time as the management information A is recorded in the control block 40 at the beginning of the magnetic tape 1, a separate control block 42 is provided after the currently written user data, and this control block 42 The same management information A2 as the first control block 40 is also recorded in the first control block 40. Furthermore, a control block 4 is installed before the physical EOT, which is the final position of the magnetic tape 1.
4, and the same management information A3 as the management information A recorded in the first control block 40 is also recorded in this control block 44.

Furthermore, three control blocks 40
, 42, and 44 include management information A, A2, and A that are set to 1 when the magnetic tape 1 is loaded or immediately after data is written, and are reset to 0 when the magnetic tape 1 is unloaded.
An update flag L indicating whether or not 3 has been updated is recorded. That is, when the magnetic tape 1 is unloaded due to a power cut, etc., the updated management information developed in the internal memory of the device, that is, the control storage 24, cannot be updated by recording on the magnetic tape 1. In this case, the update flag L indicating update remains set to 1.

Therefore, when the management information is read from the magnetic tape 1 during the next load, the update flag L is checked, and if the update flag L is set to 1, the management information was correctly updated during the previous unload. It is possible to take appropriate measures, such as prohibiting access using management information that has not been updated. Also, the update flag L of the first management information A is set to 1 when the magnetic tape is installed (loaded), and the remaining management information A2 and A3 are recorded together with the management information so that it becomes 1 immediately after writing the user data. However, all 0 when rewinding due to tape unloading.
By reverting to , you can distinguish whether the update is in progress or the last update.

Of course, data blocks 40, 42 and 44
The management method of the present invention can also be achieved by simply recording the management information A, A2, and A3 without recording the update flag L in the files. FIG. 4 is an explanatory diagram showing the first writing of user data in the management system of the present invention. In FIG. 4, when user data 1 is written following the first control block 40, file management information of the newly added user data is added to the management information developed in the control storage 24 in the control device, This management information is stored in the control block 4 immediately after the writing end position of user data 1.
Record as 2.

FIG. 5 is an explanatory diagram showing the writing of the second user data following the writing of the first user data in FIG. In FIG. 5, the second user data 2 is written over the management information of the control block 42 following the user data 1 shown in FIG. The management information of the existing data block 42 is lost.

When the writing of the user data 2 is completed, file management information regarding the newly written user data 2 is added to the management information developed in the control storage 24 in the control device, and the data immediately after the user data 2 is Management information A2' is written as block 42'. Figure 4
In FIG. 5, the management information in the first control block 40 is basically updated at the time of unloading, as will be explained later. Although it may be positioned at the top position, the management information in the control storage 24 in the control device may be recorded and updated at that time.

Furthermore, in FIGS. 4 and 5, the update flag L is set to L=1 when the management information of the control storage 24 in the control device is written and updated, and the update flag L is set to L=1 when the management information of the control storage 24 in the control device is written and updated. If the update flag L is L=0 at the next load, it is known that the update has been completed normally, and when L=1, it is known that the update has not been completed normally.

FIG. 6 is an explanatory diagram showing the management information reading process when a magnetic tape is loaded, taking as an example a case where a medium abnormality occurs in the control block at the beginning of the magnetic tape. In FIG. 6, when the magnetic tape 1 is set in the device and a loading operation is performed, the control block 40 at the beginning of the magnetic tape 1 is read into the control storage 24 in the control device.

However, assume that there is a medium abnormality in the control block 40 due to wear or deterioration, and the management information A is lost. In this case, by further advancing the magnetic tape 1 and reading the control block 42,
The read information from the first control block 40 that has caused a medium abnormality, which is stored in the control storage 24 in the control device, is transferred to the next control block 42.
The management information is rewritten to the management information that has been read normally, and the necessary processing is performed according to this normal management information.

FIG. 7 is a flowchart showing control processing when a write command is received from a host computer in the management system of the present invention. In FIG. 7, first, a load command is received from the host computer, and the tape is loaded in step S1. The tape mounting process in step S1 is shown as a subroutine in FIG.

In FIG. 8, when the tape is loaded by a loading operation in step S1, management information is read from the control block 40 at the beginning of the magnetic tape 1 in the next step S2, and is developed in the control storage 24 in the apparatus. If the management information cannot be read due to some reason such as scratches on the medium, it is determined that the management information has been lost, the tape is advanced in step S4, and the next management information is recorded in step S5. The control block is determined and the processing from step S2 is repeated.

If the management information can be read in step S3, it is determined that the management information is normal, and in step S6 the management information is stored in the control storage 24, where the update flag L (for the control block that can be read) is Set L=2. Then, in step S7, the tape is rewound to the first user data 1, and the process returns to the process of FIG.

In step S2 of FIG. 7, a write command and write data are received from the software, ie, the host computer, and data is written in step S3. When it is determined in step S4 that data writing has ended, the process advances to step S5, where the control storage 2
Create and update new management information by adding file management information regarding the newly written user data to the management information expanded in step S6, and write the management information as a control block immediately after the newly written user data in step S6. In addition, the last control block 44 and the first control block 40 of the magnetic tape are updated by writing management information at the time of unloading.

By updating the magnetic tape management information in step S6, the update flag L is set to L=1. Next, in step S7, the tape is rewound before the newly written management information, and in step S8, it is checked whether or not the write command continues. If the write command continues, the process from step S2 is repeated.

If it is determined in step S8 that the continuation of the write command has been interrupted, the process proceeds to step S9, waits for an unload command, and then proceeds to tape ejection processing in step S10. The tape ejection process in step S10 is shown in FIG. In FIG. 9, first, tape rewinding of the magnetic tape to the management information A of the control block 40 at the beginning is started.

During this tape rewinding, it is checked in step S2 whether or not the position is the management information, and if it is determined that it is the position of the management information, the process advances to step S3, and whether or not it is the top management information A is checked. If it is not the first management information A, it is management information A2 that exists immediately after the user data or management information A3 that exists at the end of the magnetic tape, so the process advances to step S4 and these management information A2 and A3 are checked.
update while rewinding the tape.

When it is determined in step S3 that the management information A is the first one, the management information A is updated as the final management information in step S5, and the tape is ejected in step S6. Also, regarding the update of the management information in steps S4 and S5, the update flag L is set at the same time as L=
Rewrite from 1 to L=0.

When the above tape ejection process is completed, the process returns to step S7, and the process for the series of write commands is completed. FIG. 10 shows the processing operation when a read command is received from the host computer. In the processing operation for the read command in FIG. 10, the reading of the management information in the tape loading in step S1 is as shown in the tape loading subroutine in FIG.
The updating of the management information in tape ejection in step S7 when the unload command is received is also as shown in the subroutine of FIG.

Steps S2 to S5 are processes unique to the read command, in which data is read from the magnetic tape in step S2, read data is sent to the software, that is, the host computer, in step S3, and step S
When it is determined in step 4 that data reading has ended, it is checked in step S5 whether or not the read command continues.If the continuation is completed, an unload command is waited for in step S6, and the process proceeds to tape ejection processing in step S7.

[0037]

Effects of the Invention As explained above, according to the present invention, even if management information regarding media and files recorded on a part of a magnetic tape is lost due to deterioration of the magnetic tape, it can be written to another location. The management information can be reliably reproduced using the management information recorded on the magnetic tape, and the reliability of access based on the management information recorded on the magnetic tape can be improved.

Furthermore, if the magnetic tape is unloaded due to a power cut, etc. before the management information of the magnetic tape is updated, the update flag can be checked at the next loading to confirm that the management information was not updated normally. be aware of this and take appropriate countermeasures.

[Brief explanation of the drawing]

[Fig. 1] Diagram explaining the principle of the present invention

[Figure 2] Configuration diagram of an embodiment of the present invention

[Fig. 3] Diagram explaining the format of the magnetic tape of the present invention

FIG. 4 is an explanatory diagram of the first user data write operation of the present invention.

FIG. 5 is an explanatory diagram of the second user data write operation of the present invention.

FIG. 6 is an explanatory diagram of the management information read operation of the present invention.

[Figure 7]
Flowchart showing write operation of the present invention

[Figure 8] Figure 7
Flowchart showing the tape loading process of

[Figure 9] Figure 7
Flowchart showing the tape ejection process of

FIG. 10 is a flowchart showing the read operation of the present invention.

[Explanation of symbols]

1: Magnetic tape 2: Management information recording means 3: Management information reading means 10: Magnetic tape storage control device 12: Magnetic tape drive device 14: Microprocessor (MPU) 16: Host interface 18: Drive interface 20: Data buffer 22: DMA controller 24: Control storage 26: DIP switch 28: Control bus 30: DMA bus 32: Drive controller 34: Drive 36: Sending reel 38: Take-up reel 40, 42, 44: Control block 46: Control track

Claims (8)

[Claims] 1. Management information regarding the medium is recorded on a magnetic tape (1), and when the magnetic tape (1) is loaded, the management information is read and developed in the device, and access is made for each medium based on the management information. In a management method for a magnetic tape storage device to be managed, a management information recording means (2) for recording the management information at a plurality of locations (A, A2, A3) on a magnetic tape (1);
The management information recorded at a predetermined specific position (A) on the magnetic tape (1) is read and expanded to the memory in the device, and the management information at the specific position (A) cannot be read normally. A management method for a magnetic tape storage device, comprising: a management information reading means (3) for reading management information at other positions (A2, A3). 2. In the management method for a magnetic tape storage device according to claim 1, the management information recording means (2) is configured to record the management information on the magnetic tape when the management information is recorded on the magnetic tape. When the management information reading means (3) reads the management information from the magnetic tape (1), the management information reading means (3) determines whether or not there is an update from the flag information and performs corresponding processing. A management method for magnetic tape storage devices characterized by: 3. In the management system for a magnetic tape storage device according to claim 1, the management information recording means (2) records a physical tape start position (physical BO) at the beginning of the magnetic tape (1).
T) and the logical start position of the user data area (logical BO
recording the management information in a first position (A) between T);
Regarding the user area, the management information is recorded in the second position (A2) following the write end position of the data file, and the physical tape final position (physical EOT) of the magnetic tape is recorded.
) A management method for a magnetic tape storage device, characterized in that the management information is recorded in a third position (A3) in front of the magnetic tape storage device. 4. In the management method for a magnetic tape storage device according to claim 3, the management information recording means (2) stores the management information in a second position (A2) following the write end position of the data file. When writing new data in a state where . A management method for a magnetic tape storage device, characterized in that the management information is recorded in a second position (A2'). 5. In the management method for a magnetic tape storage device according to claim 1, when the management information recording means (2) receives an unload command from a host device, the management information recording means expands the information into the memory within the device. A management method for a magnetic tape storage device, characterized in that management information at a plurality of positions (A, A2, A3) already recorded on a magnetic tape (1) is overwritten and updated with management information. 6. In the management method for a magnetic tape storage device according to claim 1, the management information recorded on the magnetic tape (1) includes medium management information of the magnetic tape itself and information written on the magnetic tape (1). 1. A management method for a magnetic tape storage device, characterized in that data file management information for stored user data is created and recorded. 7. A management method for a magnetic tape storage device according to claim 5, wherein a medium number, presence or absence of medium abnormality, and number of times the medium is used are recorded on the magnetic tape (1) as medium management information. A management method for magnetic tape storage devices characterized by: 8. A management method for a magnetic tape storage device according to claim 5, wherein the magnetic tape (1) includes, as file management information, a correspondence between physical position information and logical position information of a data file. A management method for a magnetic tape storage device characterized by recording relationships.