JPH09114601A - Magnetic tape recording and reproducing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a practical data transfer rate including tape exchange time. SOLUTION: A host computer 110 and a data recorder 111 are connected by an SCSI cable 113. Also, an automatic changer 112 is connected with the host computer 110. The host computer 110 is provided with a hard disk drive 114 and the data recorder 111 is provided with a memory 116 for a DIT (directory information table). A tape 115 to be mounted is supplied from the automatic changer 312 to the data recorder 111. Instead of reading the DIT from the tape by physical loading, logical loading is performed by using the write DIT command of an SCSI from the host computer 110. Further, instead of writing the DIT on the tape by physical unloading, logical unloading is performed by using the read DIT command of the SCSI.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape recording / reproducing system applicable to a helical scan type data recorder for recording digital data as oblique tracks on a magnetic tape by a rotary head.

[0002]

2. Description of the Related Art A magnetic tape device used as an external storage device such as a computer is known. As one of magnetic tape devices, a helical scan type device is known in which digital data is recorded on a cassette tape by a rotary head. In such a magnetic tape device, as a process (referred to as a load process) when writing / reading is started with respect to the tape, the header information on the tape is read after the tape is loaded and stored in the memory of the device. In addition, as a process (referred to as an unload process) for ending the read / write, the header information stored in the memory of the device is transferred onto the tape, and the tape is removed.

[0003]

As an example, a tape cassette is loaded into a data recorder by a robot,
When a plurality of tapes are exchanged and used by combining an ejecting autochanger, it takes time for loading and unloading each time the tapes are exchanged, so access to user data becomes slow. Therefore, the data transfer rate is substantially reduced. That is, in the loading and unloading operations required when exchanging tapes, DI is a table that summarizes information for managing data.
In order to read T (data information table) from the tape and write it on the tape, it is necessary to repeat the operations such as fast forward, rewind, search, read, and write of the tape. It is difficult to reduce this time only with a magnetic tape device using a tape.

Therefore, an object of the present invention is to reduce the time to read / write the table from / to the tape at the time of tape exchange, thereby improving the substantial data transfer rate including the tape exchange time. It is to provide a recording / reproducing system.

[0005]

According to the present invention, in a magnetic tape recording / reproducing system in which a data recorder and a computer are combined, a table in which information for managing data and numbers unique to the tape are recorded is recorded on the magnetic tape. The table is transferred from the computer to the data recorder when the tape is loaded, the table is stored in the data recorder, and the table is transferred from the data recorder to the computer when the tape is unloaded and the table is stored in the computer. The magnetic tape recording / reproducing system is characterized in that Further, according to the present invention, when the magnetic tape is taken into the system, the table recorded on the magnetic tape is reproduced, the reproduced table is transferred from the data recorder to the computer, and the magnetic tape is taken out of the system. Is a magnetic tape recording / reproducing system characterized in that a table stored in a data recorder is recorded on a magnetic tape.

As described above, a function for transferring the table required for high-speed access to the data on the tape between the data recorder and the computer is added. Then, by reducing the time to read / write the table from / to the tape when exchanging the tape, the substantial data transfer rate including the tape exchanging time can be improved.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Prior to the description of an embodiment of the present invention, an example of a data recorder to which the present invention can be applied will be described. The data recorder described here records / reproduces digital data on / from a cassette tape with a rotary head. 1 and 2 show the front and back of the exterior of the device, respectively.

As shown, two units stacked one above the other, namely a tape drive controller 1
And the digital information recorder 2 constitute a data recorder. The front panel of the tape drive controller 1 is provided with a button 3 for operating loading / unloading of the cassette tape, and a plurality of light emitting diodes 4 for indicating whether or not the cassette tape is loaded, a power-on state and the like. There is. A cassette tape insertion slot 5 is provided on the front panel of the digital information recorder 2. Further, other operation buttons are also arranged on the portion covered by the openable / closable panel 6.

As shown in FIG. 2, a plurality of connectors are provided on the back surface of each of the tape drive controller 1 and the digital information recorder 2. The lower tape drive controller 1 includes a data input / output connector 11, a control connector 12, and an RS232.
A C connector 13, two SCSI connectors 14a and 14b, an AC power supply input connector 15, and a DC power supply output connector 16 are provided.

On the other hand, the digital information recorder 2 is provided with a data input / output connector 21, a control connector 22, and an RS232C connector 23. The operating power of the digital information recorder 2 is supplied by connecting a connection cable to the DC power output connector 16 of the tape drive controller 1. The data input / output connectors 11 and 21 are connected by a cable, and the data flow is transmitted and received between the controller 1 and the recorder 2.
The control connectors 12 and 22 are connected by a cable to exchange control signals. further,
The RS232C connectors 13 and 23 are provided for diagnosis.

As shown in FIG. 3, the host computer 2
When connecting 0 and the data recorder, the SCSI connectors 14a and 14b are used. When the host computer 20 gives a read command to the data recorder, for example, the data recorder outputs the data to the host computer 20.

The digital information recorder 2 records / reproduces digital data on / from a cassette tape with a rotary head. FIG. 4 shows an example of the head arrangement of the recorder 2. Drum 2 rotating at a predetermined speed in the direction shown
Four heads Ra, Rb, Rc and Rd for recording and four heads Pa, Pb, Pc and Pd for reproduction are attached to the disk 5, respectively.

The heads Ra and Rb are provided in close proximity to each other, and similarly, the heads Rc and Rd, the heads Pa and Pb, and the pair of heads Pc and Pd are provided in close proximity to each other. Further, the extension direction (called azimuth) of the gap between these two adjacent heads is different. Heads Ra facing each other at 180 ° intervals
And Rc has a first azimuth, similarly 180 °
Heads Rb and Rd facing each other at a distance of 2 have a second azimuth. The heads Pa and Pc have the first azimuth, and the heads Pb and Pd have the second azimuth. The different azimuths are used to prevent crosstalk between adjacent tracks. The two adjacent heads are actually realized as an integrally structured head called a double azimuth head.

A tape (for example, 1/2 inch width) pulled out from the cassette is obliquely wound around the peripheral surface of the drum 25 over an angular range slightly larger than 180 °. The tape is fed at a predetermined speed. Therefore, at the time of recording, in the first half of the period in which the drum 25 makes one rotation, the head Ra
And Rb scan the tape, and in the latter half, the heads Rc and Rd scan the tape. During playback, the head Pa
And Pb scan the tape, then heads Pc and Pd scan the tape.

FIG. 5 shows a track pattern on the tape of the digital information recorder 2. Longitudinal tracks are formed on the upper and lower sides of the tape in the width direction, and helical tracks are formed between them. Upper longitudinal track 2
A control signal is recorded in 6 and a time code is recorded in the lower longitudinal track 27. The time code indicates the longitudinal position of the tape,
For example, SMPTE time code is used. Drum 2
In one rotation of 5, the heads Ra and Rb simultaneously form two helical tracks Ta and Tb, and then the heads Rc and Rd simultaneously form two helical tracks Tc and Td. It should be noted that each helical track is formed by separating the first half portion and the second half portion, and a tracking pilot signal recording area 28 is provided in the middle portion.

The SMPTE time code was developed for a video signal such as a VTR, and its minimum unit is a frame (1/30 second). As will be described later, the data recorder has four tracks Ta to Td shown in FIG.
Is a logical data unit of data (referred to as a track set) that handles recordable data. For example, in the case where 16 tracks correspond to one frame of a video signal, the lower digit (value of 0, 1, 2, or 3) of the digit of the frame of the time code is provided and the track set is set as a unit. It is necessary to use a time code (also referred to as an ID) to be used. In case of SMPTE time code,
Since the user data area is prepared, this kind of modification is possible.

FIG. 6 schematically shows the system configuration of the tape drive controller 1 and the digital information recorder 2. System controller 31 in controller 1
The main features of are: Management of SCSI controller 32 Management of buffer memory 33 File management / table management Data writing, reading, retry management Digital information recorder 2 control Self-diagnosis

A connection with the host computer is made via the SCSI controller 32. Buffer memory 33
A drive controller 34 is provided between the tape controller and the tape drive controller. The data read from the buffer memory 33 is supplied to the C2 encoder 35 via the drive controller 34. C2 encoder 3
5 to the track interleave circuit 36 and C1
The encoder 37 is connected.

The C2 encoder 35 and the C1 encoder 37 are for performing error correction coding of the product code on the recording data. Further, the track interleave circuit 36 controls distribution of data to tracks when recording data in order to improve the ability to correct errors that occur in the recording / reproducing process.

Further, when data is recorded on the tape, since the SYNC block divided by the sync signal is a unit, the track interleave circuit 36 adds the block sync signal. Further, in the C1 encoder 37, after the C1 parity is generated, data randomization and word interleaving processing in a plurality of SYNC blocks are performed.

Digital data from the C1 encoder 37 is transmitted to the digital information recorder 2. The digital information recorder 2 includes a channel code encoder 38.
The digital data received in step 3 is encoded, and the print data is output to the print heads Ra to Rd via the RF and amplifier 39. Recording data is recorded on the tape by the heads Ra to Rd. The RF / amplifier 39 processes the partial response class 4 (PR (1,0, -1)).

The data reproduced from the tape by the reproducing heads Pa to Pd is supplied to the channel code decoder 42 via the RF and amplifier 41. RF, amplifier 41
Includes a reproduction amplifier, an equalizer, a Viterbi decoder, and the like.
The output of the channel code decoder 42 is transmitted to the tape drive controller 1 and input to the C1 decoder 43.

A track deinterleave circuit 44 is connected to the C1 decoder 43, and a C2 decoder 45 is further connected to the deinterleave circuit 44. The C1 decoder 43, the track deinterleave circuit 44, and the C2 decoder 45 respectively include a C1 encoder 37, a track interleave circuit 36, and a C2 encoder.
A process opposite to the process performed by each of the encoders 35 is performed. The reproduction (read) data from the C2 decoder 45 is transferred to the buffer memory 33 via the drive controller 34.
Supplied to

The digital information recorder 2 is provided with a system controller 46. Also, a fixed head 47 is provided for the tracks in the longitudinal direction of the tape,
The head 47 is connected to the system controller 46, and the head 47 records / reproduces a control signal and a time code. The system controller 46 is connected to the system controller 31 of the tape drive controller 1 via a bidirectional bus.

A mechanism controller 48 is connected to the system controller 46. The mechanism controller 48 includes a servo circuit and drives a motor 50 via a motor drive circuit 49. The system controller 46 has, for example, two CPUs, communicates with the tape drive controller 1 and records / records time codes.
The system controller 46 controls reproduction, recording / reproduction timing, and the like.

The mechanism controller 48 is, for example, 2
It has CPUs and controls the mechanical system of the digital information recorder 2. More specifically, the mechanism controller 48 controls header / tape system rotation control, tape speed control, tracking control, cassette tape loading / unloading control, and tape tension control. The motor 50 generally represents a drum motor, a capstan motor, a reel motor, a cassette mounting motor, a loading motor, and the like.

Further, DC to which the DC voltage from the power supply unit 51 of the tape drive controller 1 is input
A -DC conversion circuit 52 is provided. Although not shown in the figure, the digital information recorder 2 includes a position sensor such as a tape end detection sensor and a time code generator /
A reading circuit and the like are provided.

Next, the format for recording digital data will be described. First, the layout of the entire tape (for example, the tape in one cassette) is shown in FIG. The entire tape is a physical volume. A physical tape beginning PBOT (Physical Beginning of Tape) and an end P to which a leader tape is connected.
Areas that can be recorded between EOT (Physical End of Tape) are LBOT (Logical Beginning of Tape) and L
It is between EOT (Logical End of Tape). This is because the tape is easily damaged at the beginning and end of the tape and the error rate is high. As an example, the dead area between PBOT and LBOT is defined as 7.7 ± 0.5 m, and the dead area between LEOT and PEOT is 10
Specified as greater than m.

In order to manage one or more logical volumes (also called partitions), a VSIT (Volume Set Information Table) is recorded at the beginning of the recording area. VSIT has the number of volumes recorded on the tape and position information of each logical volume on the tape.
The position information is the physical ID of each VIT of the maximum 512 logical volumes, the final physical ID, and the logical ID of the VIT.
It is. Further, the flag indicating the presence / absence of UIT of each logical volume is also included in VSIT.

The position of the beginning of VSIT is the position of 0-ID. The ID is an address corresponding to a position on the tape that is assigned to each set of four tracks. From the VSIT area to the DIT area of the last volume, the ID is added monotonically. The length of one VSIT is 1-ID
It is.

A logical volume is a DIT (Directory Inf
ormation table), UIT (User Information Table) and user data area. The DIT has information for managing files in the logical volume. The length of one DIT is 40-ID. UIT is optional. UIT is user-specific information for managing files.

In FIG. 7, the shaded area is a run-up area. The data track is servo-locked by the run-up area. The area with dots is a position margin band. This position margin band prevents erasing valid data when VSIT and DIT are updated.

VSIT is repeatedly recorded 10 times, as shown in FIG. 8A, in order to improve the reliability of data. Therefore, the VSIT area is 10 track sets (= 10-ID). 90 after the VSIT area
A retry area larger than the track set is secured.

The DIT is repeatedly recorded seven times as shown in FIG. 8B in order to improve the reliability of the data. The DIT is composed of 6 tables as shown in FIG. 8C. The six tables are
T (Volume Information Table), BST (Bad Spot Tabl)
e), LIDT (Logical ID Table), FIT (File Inform
application table), UT (Update Table), UIT (User Info)
rmation Table). VIT, BST, LIDT, U
T has a length of 1-ID and FIT has a length of 20-ID. The remaining 16-ID area is reserved.

Each table of DIT will be described. V
The IT ID address is the top physical ID of the volume written in VSIT, and its logical ID is VSI.
It is the head logical ID of the volume written in T. V
The IT includes volume information such as the volume label, the starting physical ID of the first data block in the physical volume, and the last physical ID thereof.

The ID address of BST is the physical I of VIT.
D + 1 and its logical ID is VIT logical ID + 1
It is. The BST contains logically invalid data information.
Logically invalid data is data that should be treated as invalid because data having the same track set ID is written later. For example, as shown in FIG. 9, the shadow area A is logically invalid data. The write retry operation and the write operation associated with it cause logically invalid data. If an error occurs during writing, write retry is automatically performed, the error location is output, and this is registered in BST. Then, during the read operation, the invalid area is designated by the BST. Data that is logically invalid is also called a bad spot. The BST manages start physical IDs and end physical IDs of up to 14592 bad spots.

The ID address of the LIDT is the physical ID of VIT + 2, and its logical ID is the logical ID of VIT +
2. LIDT is a data table for fast block space and locate operations.
That is, the logical ID of each pointer of the first to 296th pointers, its physical ID, file number, I
The first block number in the D data block management table is included in the LIDT.

The ID address of the FIT is the physical I of the VIT.
D + 3, and its logical ID is VIT logical ID + 3
It is. The FIT is composed of two types of data pairs corresponding to the tape mark. The tape mark is the delimiter code of the file. The Nth data pair corresponds to the Nth tape mark from the beginning of the volume. One data of the pair is the physical ID of the Nth tape mark. This value is the physical track set ID of the tape mark
It is. The other data is the absolute block number of the Nth tape mark. This value is the absolute block number of the last block with the same file number as the tape mark. Since the position of the tape mark is known, the physical position on the tape can be accessed at high speed.

The ID address of the UT is the physical ID of the VIT
It is +39. UT is information indicating whether or not the volume has been updated. Before the update, the word (4 bytes) indicating the update status in the UT is FFFFFFFFh.
(H means hexadecimal), and after updating, this is set to 00000000h.

The UIT is optional and is, for example, a 100-ID area. It is a data table accessible to the user and is reserved for the user header.

In this example, 1-ID is assigned to each track set consisting of four helical tracks. The logical structure of the data block is defined for each track set. FIG. 10 shows a logical track set structure. The first 4 bytes of the logical track set is the format ID, which is FFFF0000h.

The next 136 bytes (34 words) is an area for subcode data. The subcode data consists of management information of the related track set. For example, the ID of the above-mentioned table (VSIT, VIT, BST, etc.)
Is included in the subcode.

Further, the number of bytes obtained by removing the length of the block management table from the next 11684 bytes is the area of user data. If the size of the user data does not reach the specified size, the dummy data is packed in the remaining area. The formats of the track set defined in the user data area include user track set, tape mark (TM) track set, and EOD (End Of Dat).
a) There are four types: track set and dummy track set. A subcode and a block management table are defined for each format of these track sets.

A block management table area is provided after the user data area. The block management table is
The maximum length is 4096 bytes. The last 4 bytes of the track set are the end code of the track set (0F0
F0F0Fh), and the previous 12 bytes are reserved. The block management table manages the data block configuration of user data.

The logical format of the above data recorder is shown in FIG. VSIT is recorded for each physical volume such as one tape. A DIT is recorded for each logical volume (partition), and five tables VIT, BST, LIDT, and FI are recorded in the DIT.
T, UT are included, and UIT is optionally included. Further, a track set is defined for every 4 helical tracks, and four types of user track sets, a tape mark track set, an EOD (End Of Data) track set, and a dummy track set are defined in the user data area in the track set. It

Now, an outline of the operation of the above data recorder will be described. First, when using the first tape, it is necessary to initialize the tape. In the tape initialization operation, VSIT, DIT, and EOD are written in predetermined positions, and dummy data are written.

When reading / writing a tape, the tape is loaded. After the tape is inserted, the button 3 is pressed to perform the loading operation. VSI on load
T and DIT are read. When the reading / writing of the tape is finished, the tape is unloaded by pressing the button 3. VSIT and DI when unloading
T is rewritten. The load operation and the unload operation can be performed by a command other than the operation of the button 3.

FIG. 12 shows the tape drive controller 1
The system configuration of is shown in more detail. 61 is the main CP
U, 70 is 2-port RAM, 80 is bank memory, 81
Is a sub CPU. The main CPU 61 is a CPU that manages the entire system. A CPU bus 62 is provided in association with the main CPU 61, and each component is coupled to the CPU bus 62. That is, ROM (flash ROM) 63, PIO (parallel I / O) 64,
The PIO 65, the control panel 66, the LCD 67, the timer 68, the RS232C interface 69, the 2-port RAM 70, and the RAM 71 are connected.

The PIO 65 is connected to the buttons on the front panel. The LCD 67 is a display device that displays the operating status of the drive so that the user can see it. RS2
The 32C interface 69 is connected to the serial terminal. The RAM 71 is a work R used by the firmware.
It has an AM, a program download area, and an area for temporarily storing header information (VSIT / DIT).

Unidirectional control element 7 for CPU bus 62
The IM bus 74 is connected via the terminal 3. This IM bus 7
4, S-RAM 72, bank memory 80, SC
The SI controller 75 is connected. A host computer is connected to the SCSI controller 75 via the SCSI bus 76. The S-RAM 72 is a capacitor backup RAM, a script RAM,
It is also a memory that actually holds logger data.
This memory can hold data for about two days after the power is turned off.

The two-port RAM 70 has two CPUs 6
Five types of packets for communication of information between 1 and 81 are stored. These are: Command transmission packet: a packet used when requesting the CPU 61 to 81 to execute an operation. End status reception packet: a packet used for notifying the end status when the CPU 81 executes a command requested by the CPU 61 and the operation ends. Command status; a flag for indicating the progress of the command. Drive management status table; drive status is C
This is a table for notifying the PU 61. This table is rewritten by the CPU 81 at regular intervals. Data transmission / reception packet; a buffer used when the firmware on the drive (recorder) side is downloaded via the SCSI bus, or when the drive side diagnostic is activated using the serial port of the CPU 61. The bank memory 80 is a buffer memory for data.

The sub CPU 81 is a CPU for controlling the drive. CPU bus 8 associated with sub CPU 81
2 is provided, and a ROM (flash RO
M) 83, RAM (work RAM) 84, timer 8
5, RS232C interface 86, RS422 interface 87, PIO (processor control) 88, and DMA controller 89 are connected, and further, 2-port RAM 70 and bank memory 80 are connected.

The bank memory 80 is a bank memory for storing data on the tape. For example, the bank memory 80 has eight memory banks, and write data or read data is stored here. A DMA (Direct Memory Access) controller 89 is a controller for pasting the data written in the drive to the bank memory 80. RS232C interface 86
Is for diagnostics. The RS422 interface 87 is a communication means with the drive.

FIG. 13 shows the loading process (that is, the process of reading VSIT and DIT from the tape). The SCSI controller 75 receives a load request from the host computer, or the PIO 65 recognizes that the user has pressed a button. Thereby, the main CPU
61 recognizes that there is a load request. Then C
The PU 61 requests the CPU 81 to rewind the tape. When the tape rewinding operation is performed, the position of the head is the tape top as shown in FIG. 13A.

Next, the virgin tape is checked. This is an operation of skipping 5600-ID from the tape top. As shown in FIG. 13B, the head position is V
It becomes the head of SIT.

Then, VSIT is read from the 0-ID, whereby the start position / end position for the first volume is acquired. FIG. 13C shows the head position when reading VSIT.

Next, the DIT reading process is performed. That is, as shown in FIG. 13D, 1720-ID to 40
-Read DIT for each ID (length of one DIT).

Then, from 1720 to 19991-ID, D
Rewrite IT. This is a process of setting a flag indicating the update status of the UT. Figure 13E shows this DI
This is the head position when T is rewritten. Finally, FIG.
As shown in F, preroll to the beginning of the user area.

Next, the unloading process of the data recorder (the process of returning the data on the memory (RAM 71) to the tape) will be described with reference to FIG. First, the SCSI controller 75 receives an unload request from the host computer, or the PIO 65 recognizes that the user has pressed a button. Thereby, the main C
The PU 61 recognizes that there is an unload request. Then, the CPU 61 requests the CPU 81 to preroll from the current position to the beginning of the DIT. The position of the head in the pre-rolled state is the head position of the DIT as shown in FIG. 14A.

Next, 1720-ID to 19991-ID
Rewrite DIT to. This is necessary to keep the UT's flags updated. FIG. 14B shows the position of the head in this case.

Then, the rewinding operation is performed, and the position of the head is set to the tape top, as shown in FIG. 14C. In this way, the eject operation is performed with the head position being the tape top. Although the ejecting operation may damage the tape, the effect of this damage can be reduced because the tape is ejected at the position of the tape top.

FIG. 15 schematically shows the flow of DIT when loading and unloading the data recorder as described above. In FIG. 15, 101 is the DI on the tape
T indicates a memory of the data recorder, more specifically, DIT on the RAM 71 (see FIG. 12). D
When the tape on which IT is recorded is put in the data recorder, the DIT is first read from the tape onto the memory of the data recorder (load). By this loading operation, the positions of all user data can be known in advance. Therefore, the tape can be moved to the position of the user data designated by the DIT at high speed without reading the user data from the tape one by one.

The DIT thus recorded on the tape is conceptually shown in FIG. 16A. In this example, DIT and user data No. 1 to No. Addresses 1 to 1
8 is attached. The address is specifically the value of the ID described above. Then, in the DIT, the user data No. shown in FIG. 1 to No. The respective start addresses corresponding to 4 are recorded. Therefore, as can be seen from the DIT shown in FIG. 16B, the user data No. The top address corresponding to 1 is 3, and the user data No. 2
The start address corresponding to is 7. In addition, the user data No. The top address corresponding to No. 3 is 11, and the user data No. The start address corresponding to 4 is 15.

Further, the DIT is changed on the memory of the data recorder by adding or deleting the user data of the tape. Therefore, there is no delay in the access time to the user data due to the DIT change. Further, when the tape is ejected from the data recorder, the modified DIT stored in the memory of the data recorder is written (unloaded) on the tape. By this unload operation, D
IT is uniquely managed on each tape.

In FIG. 17, the data recorder displays D on the tape.
The processing when the user data of the tape managing the IT is accessed three times and the DIT is changed is shown. FIG.
17A shows the case of one tape, and FIG. 17B shows the case of 3 tapes.
This is the case for books. In FIG. 17, in comparison with the case of one tape shown in FIG. 17A, in the plurality of tape exchanges shown in FIG. 17B, when the tape is taken in and out of the data recorder, the DIT is read / written from / to the tape. The load operation requires time. That is, in the method of managing the DIT on the tape, access to the user data is slow when the tape is exchanged, and the data transfer rate is substantially reduced. Therefore, the present invention constitutes a system for managing the DIT by the host computer in order to eliminate this drawback.

FIG. 18 shows a magnetic tape recording / reproducing system according to an embodiment of the present invention, more specifically, an automatic tape changing system. Further, the flow of DIT of the magnetic tape recording / reproducing system according to the present invention is schematically shown in FIG. In FIG. 18, 111 is a data recorder similar to that described above. In order to transfer user data and control the data recorder 111, the host computer 11
0 and the data recorder 111 are connected by a SCSI cable 113. Furthermore, by adding two commands, write DIT and read DIT, to the existing command as the SCSI command, the host computer 1
The DIT can be transferred between the data recorder 10 and the data recorder 111. The host computer 110 includes, for example, a hard disk drive 114 as a storage device.

Further, for the data recorder 111,
The tape 115 loaded is the autochanger 112.
Supplied from The autochanger 112 is connected to the host computer 110, takes out a tape (tape cassette) designated by the host computer 110 from the shelf in which the cassette is stored, loads the tape on the data recorder 111, and the host computer 110. The cassette ejected from the data recorder 111 is stored on the shelf in response to a command from the.

As a method of managing the DIT, as in the data recorder described above, the DI is read from the tape at the time of loading.
There is a method of reading T, storing the read DIT in the memory of the data recorder, and writing the DIT stored in the memory at the time of unloading onto the tape. Such loading and unloading is called physical loading and physical unloading.

On the other hand, in one embodiment of the present invention,
In the tape automatic exchange system shown in FIGS. 18 and 19, when the tape is first brought in from the outside, physical loading is performed, and the DIT and the tape-specific number are transferred to the hard disk drive 114 of the host computer 110 through the SCSI cable 113. Store as a database. After that, when the tape is taken in and out in the system, the DIT stored in the hard disk drive 114 is read or rewritten instead of the process of reading the DIT from the tape or writing to the tape.

DI of this hard disk drive 114
The process of reading T and transferring it to the memory 116 of the data recorder 111 via the SCSI cable 113 is called a logical load, and the process of reading the DIT of this memory 116 and transferring it to the hard disk drive 114 via the SCSI cable 113 is performed. It is called a logical unload.

That is, in one embodiment of the present invention, instead of reading the DIT from the tape by physical loading, the SCSI write DIT command from the host computer 110 is used to perform logical loading. Then, instead of writing DIT on the tape by physical unloading, logical unloading is performed using the SCSI read DIT command. In this way, the physical loading and unloading processes at the time of exchanging the tape are not required, and it is possible to prevent the access speed from being substantially reduced.

When the SCSI interface is used, even if the DIT has a size of 4 Mbytes, the DI
It is possible to transfer T in less than 1 second. If the DIT is transferred during injecting and threading or ejecting the tape, this time can be completely ignored.

Here, when managing a plurality of DITs on the host computer 110, the problem is a tape and a D.
IT consistency. In the conventional method, since the DIT was managed on the tape, the DIT of another tape was not accidentally loaded into the data recorder 111.
However, when the DIT is managed by the host computer 110 as in the embodiment of the present invention, there is a possibility that the tapes will be replaced, so it is necessary to confirm it by some method.

A generally conceivable method is a method in which a bar code label is attached to a tape for management. However, the labor and time required to attach the barcode to the tape and the barcode reading device are required, which leads to an increase in cost.
Further, in the method using the volume label, the volume label needs to be read from the tape, so the effect of omitting the DIT reading from the tape is lost.

Therefore, in one embodiment of the present invention, the initialization number recorded in addition to the data is used. The initialization number is a unique number (random number) determined when the tape is initialized, and the same initialization number is written in each subcode in the same tape. Since this initialization number is also added to the DIT, the tape can be identified by comparing the initialization number of the DIT transferred from the host computer 110 with the initialization number added to the data on the tape. .

Since the initialization number reproduced from the position on the arbitrary tape can be used in this comparison, the identification can be realized by reading some data during the positioning operation performed after the injection and threading, and the extra time can be realized. Is not required at all. Further, even if the tape is initialized again and the DIT stored in the host computer 110 and the DIT on the tape do not match, the initialization number is changed, so that the identification can be performed.

FIG. 20 shows the host computer 11 described above.
An example of the database registered in the hard disk drive 114 of 0 is shown. In FIG. 20, the tape ID 0
In 001, the volume label is data 1, and the bin number (the number corresponding to the position where the cassette is stored) is 100.
1, DIT is set to 1. Also, the tape ID 0002
Has a volume label of data 2 and a bin number of 122.
3, DIT is set to 2. And the tape ID 000
Similarly, volume label 3, bin number, and DIT are also registered in item 3. The volume label is a material name given by the user, and the bin number is data indicating a place where the tape cassette is stored.

A system for automatically exchanging tapes originally needs a database for managing a large number of tapes, and the above-mentioned data of tape ID, volume label and bin number are included in such a database. Therefore, a database as shown in FIG. 20 can be realized by adding DIT to this database. Further, in this embodiment, since the DIT is 4 Mbytes, 100 tapes have 400 Mbytes,
Hard disk drive 1 of host computer 110
It manages with 14. As described above, when the number of tapes is large or a plurality of DITs are present on the tape in the multi-volume, the database to be managed becomes too large. Therefore, when the DITs are transferred to the host computer 110, a redundant portion is created. It is preferable to perform compression.

FIG. 21 shows a flowchart of the logical load operation of the data recorder 111 in the embodiment of the present invention. In FIG. 21, in step S1, the data recorder 111 threads the tape 115 injected by the autochanger 112. That is, the tape is pulled out from the cassette and positioned on a predetermined traveling path. In the next step S2, the write DIT command is received from the host computer 110, and the process proceeds to the next step S3. In step S3, the tape position of the tape 115 threaded by the data recorder 111 in step S1 is confirmed, and the process proceeds to step S4. In step S4, the DIT is set to the hard disk drive 11 of the host computer 110.
4 to receive. Then, the process proceeds to the next step S5.

In step S5, the format of the DIT received in step S4 is checked and stored in the DIT memory 116. Then, the process proceeds to the next step S6. In step S6, the data recorder 111
It is determined whether the tape position of the existing tape 115 is the top of the tape. If the tape is at the top position, the process proceeds to step S7, the tape is moved to the first data, and the process proceeds to step S9. If it is not at the top position of the tape, the process proceeds to step S8, the tape is moved slightly forward, and the process proceeds to step S9. In step S9, the tape 115 is read, and the process proceeds to step S10.

At the next step S10, whether the initialization number included in the DIT received from the hard disk drive 114 at step S4 matches the initialization number included in the data read from the tape 115 at step S9. It will be decided. If the initialization numbers match, the process proceeds to step S11, and Good is sent to the host computer 1
10 is notified and a logical load state is set. If the initialization numbers do not match, the process proceeds to step S12, and it is determined whether the tape 115 has been read by a certain amount. If not, the process returns to step S10. If a certain amount of data has been read, the process moves to step S13, and an error is notified to the host computer 110 by a check condition.

FIG. 22 shows a flow chart of the logical unload operation of the data recorder 111 in the embodiment of the present invention. 22, in step S11, a read DIT command is received from the host computer 110. In the next step S12, the DIT on the DIT memory 116 of the data recorder 111 is transferred to the hard disk drive 114 of the host computer 110, and the process proceeds to step S13. In step S13, a logical unload state is set, and the process proceeds to next step S14. In step S14, the eject command is received from the host computer 110, and the process proceeds to step S15. In step S15, the tape 115 existing in the data recorder 111 is ejected by the autochanger 112.

Here, outside the magnetic tape recording / reproducing system of the present invention, physical loading and physical unloading are performed, and DIT is managed on the tape.
When the tape is placed in the system according to the invention, the tape DIT has not yet been registered in the hard disk drive 114 of the host computer 110. Therefore, when the tape is first put into the data recorder 111, the physical loading from the tape is performed by the mount DIT command.

When the automatic changer 112 ejects the tape from the data recorder 111, the hard disk drive 114 of the host computer 110 is logically unloaded by the read DIT command to suck up the DIT. Next, when using this tape, execute the write DIT command to the host computer 11
Logical load is performed from the 0 hard disk drive 114. While there are tapes in the system, only logical load and logical unload can be performed, and the tape exchange time can be shortened.

When the tape is taken out of the system according to the present invention, the tape is put into the data recorder 111 by the autochanger 112 and the hard disk drive 1 of the host computer 110 is executed by the write DIT command.
After performing the logical load from 14, the tape is physically unloaded to the tape by the unmount DIT command.
Thus, by physically unloading the tape and then taking it out of the system, normal use is possible.

FIG. 23 shows an example of the required time for each of the physical load and the logical load.
In FIG. 23, the physical load operation requires a total of 54 seconds from injection to preroll, whereas the logical load operation can reduce the total time to 16 seconds. In addition, FIG. 24 shows an example of the required time for each of the physical unload and the logical unload. In FIG. 24, the physical unload operation requires a total of 36 seconds, whereas the logical unload operation can reduce the total time to 10 seconds. in this way,
The time required for tape replacement can be greatly reduced.

FIG. 25 shows an example of a conventional magnetic tape device for performing physical loading / unloading and an actual transfer rate in the case of performing logical loading / unloading according to the present invention. FIG. 25 shows an example of a write operation for recording for 104 seconds. In FIG. 25, in the conventional magnetic tape device, the transfer data amount is 1040 Mbytes and the total time is 260 seconds, so that the actual transfer rate is 4
It is M bytes / s. On the other hand, in the magnetic tape recording / reproducing system according to the present invention, the total time is 130 seconds and the actual transfer rate is 8 Mbytes / s. Therefore,
The real transfer rate has been doubled.

In the above-described embodiment of the present invention, in the unloading process, the tape is rewound to the tape top, and in the next loading process, the tape top is jumped to the target DIT. However, the rewinding process to the tape top is performed. An unload process that does not perform is also possible. Further, the present invention can be applied not only to a rotary head type data recorder but also to a data recorder that performs sequential access.

Further, the data format for giving the attribute of the tape mark is not limited to the above-mentioned embodiment, and various formats are possible.

[0090]

The present invention can improve the substantial data transfer rate including the tape exchange time by about twice by reducing the time for the DIT to read and write to the tape.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a data recorder to which the present invention can be applied.

FIG. 2 is a schematic rear view of a data recorder to which the present invention can be applied.

FIG. 3 is a schematic diagram showing a usage example of a data recorder to which the present invention can be applied.

FIG. 4 is a schematic diagram showing a head arrangement of a data recorder to which the present invention can be applied.

FIG. 5 is a schematic diagram showing a track pattern of a data recorder to which the present invention can be applied.

FIG. 6 is a block diagram showing a system configuration of a data recorder to which the present invention can be applied.

FIG. 7 is a schematic diagram showing a tape format of a data recorder to which the present invention can be applied.

FIG. 8 is a VSI of a data recorder to which the present invention can be applied.
It is an approximate line figure showing the format of T and DIT.

FIG. 9 is a BST of a data recorder to which the present invention can be applied.
It is a schematic diagram for explaining.

FIG. 10 is a schematic diagram for explaining a logical format of a data recorder to which the present invention can be applied.

FIG. 11 is a schematic diagram for explaining the format structure of a data recorder to which the present invention can be applied.

FIG. 12 is a more detailed block diagram of a system configuration of a data recorder to which the present invention can be applied.

FIG. 13 is a schematic diagram for explaining load processing of a data recorder to which the present invention can be applied.

FIG. 14 is a schematic diagram for explaining unloading processing of a data recorder to which the present invention can be applied.

FIG. 15 is a DIT at the time of loading and unloading of the data recorder for explaining the embodiment of the present invention.
It is a block diagram showing the flow of.

FIG. 16 is a schematic diagram showing an example of DIT recorded on a tape for explaining an embodiment of the present invention.

FIG. 17 is a schematic diagram for explaining an example of processing according to an embodiment of the present invention.

FIG. 18 is a block diagram showing a magnetic tape recording / reproducing system according to an embodiment of the present invention.

FIG. 19 is a block diagram showing the flow of DIT in the magnetic tape recording / reproducing system according to the embodiment of the present invention.

FIG. 20 is a schematic diagram showing an example of a database registered in a hard disk drive of a host computer in an embodiment of the present invention.

FIG. 21 is a flowchart showing the operation of the logical load of the data recorder in the embodiment of the present invention.

FIG. 22 is a flowchart showing a logical unload operation of the data recorder in one embodiment of the present invention.

FIG. 23 is a schematic diagram showing an example of required times when performing a physical load and a logical load.

FIG. 24 is a schematic diagram showing an example of required times when performing physical unloading and logical unloading.

FIG. 25 is a schematic diagram showing an example of a substantial transfer rate between a conventional magnetic tape device and a magnetic tape recording / reproducing system according to the present invention.

[Explanation of symbols]

 110 Host Computer 111 Data Recorder 112 Auto Changer 113 SCSI Cable 114 Hard Disk Drive 115 Tape Cassette 116 DIT Memory

Claims (2)

[Claims] 1. In a magnetic tape recording / reproducing system in which a data recorder and a computer are combined, a table summarizing information for managing data and a tape-specific number is recorded on a magnetic tape, and when the tape is loaded, Transfer the table from the computer to the data recorder, store the table in the data recorder, transfer the table from the data recorder to the computer when the tape is unloaded, and transfer the table to the computer. A magnetic tape recording / reproducing system characterized by being stored. 2. The magnetic tape recording / reproducing system according to claim 1, wherein when the magnetic tape is taken into the system, the table recorded on the magnetic tape is reproduced, and the reproduced table is used as the data. A magnetic tape recording / reproducing system characterized in that a table stored in the data recorder is recorded on the magnetic tape when the magnetic tape is taken out of the system by transferring from the recorder to the computer.