JPH02249107A - Positioning control system - Google Patents

Abstract

PURPOSE:To perform accurate positioning without decreasing throughput and without erasing a part of a block written just before by checking the recording state of a magnetic tape when overrun occurs in a write operation. CONSTITUTION:A means 10 which performs the re-positioning of the magnetic tape to the position of a data block to be written next replying to the detection of command overrun, and a means 5 which checks the recording state of data at the position on the magnetic tape after the repositioning are provided. And such control that the data block is written at the next position when no data is written at that position, and the re-positioning of the magnetic tape is performed to the position where no data is written, then, the data block is written at the next position when the data is written at that position is applied. In such a way, it is possible to perform the precise positioning so as to write the next block without decreasing the throughput and without erasing the rear edge of a block area written just before.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a positioning control method, and more particularly to a positioning control method for controlling the repositioning operation of a magnetic tape device operating in a streaming mode.

Prior Art Conventionally, there are the following two methods of positioning control in this type of magnetic tape device.

The first method, as shown in FIG. 2, is that if a command overrun is detected when attempting to write data to the Nth block area 21, the magnetic tape is moved to position E using a capstan copulse. Return the read head to N-1.
At a position F in the interval F before the position of the block area 20, the N-1 block area 20 is read out.

At this time, the block number is checked, and if the block number is the N-1st block number, rewriting is performed.

The second method is to move the magnetic tape back to position J using the capstan copulse when a write head is detected in the N-th block area 21, and to move the write head position after the N-1st block area 22. This is a method of controlling the positioning so that it is at the block interval of .

In the first conventional positioning control method described above, in FIG. Blower area 20
Since repositioning is performed after reading out the block area 20 and checking that it is the N'-1st block area 20, there is a drawback that the execution time of the command from the host device becomes longer and the throughput deteriorates.

In addition, in the second positioning control method, since repositioning is performed by counting the capstan's tacho pulse, the write head may return too far due to the slip between the capstan and the magnetic tape, resulting in N-1 in Figure 2. There is a drawback in that it is positioned at position M after the block area 22, writes the N-th block area 23 from there, and erases the trailing edge of the N-1 block area 21 after position M.

OBJECTS OF THE INVENTION An object of the present invention is to enable correct repositioning for writing the next block without deteriorating throughput and without erasing the trailing edge of the previously written block area. An object of the present invention is to provide a positioning control method for a magnetic tape device.

According to the present invention, positioning in a streaming mode magnetic tape device performs an operation to reposition a magnetic tape relative to a head when a command overrun is detected while writing a data block to a predetermined position on a magnetic tape. A control system comprising: means for repositioning the magnetic tape to the position of the next data block to be written in response to the command overrun detection; and means for repositioning the magnetic tape to the position of the next data block to be written; A means for checking the recording state is provided, and when data is not written at this position, a data block is written at the next position, and when data is written, the magnetic tape is repositioned to the unwritten position. A positioning control method characterized in that a data block is controlled to be written in the next position is obtained.

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. As shown in FIG. 1, the read circuit 3 inputs a signal from the read head 1 via the integrated amplifier 2, and outputs it to the overrun detection circuit 4 and recording state check circuit 5.

The write circuit 7 receives the control of the command control circuit 6 and supplies a write signal to the write head 9 via the write amplifier 8 to write on a magnetic tape (not shown). The capstan motor 2 that drives the magnetic tape is equipped with an optical tachometer 3.
is attached, and the output of the optical tachometer 3 is given to a tacho pulse number circuit 14.

The travel control circuit 10 uses the output of the overrun detection circuit 4 and the output of the tachometer pulse counting circuit 14 as human power, and sends a forward signal 16 to the servo amplifier 11 that drives the capstan motor 2 under the control of the command control circuit 6. , sends out a reverse signal 17.

During normal operation, the command control circuit 6 receives a signal 18 from the main body (not shown) of the magnetic tape device, outputs write data and sends it to the write circuit 7, monitors the output of the recording status check circuit 5, and controls the running control circuit. The magnetic tape drive information is output to 10.

Next, the operation when an overrun occurs while writing a block to the magnetic tape will be described. In Figure 2, points A, B, C, D, and E.

F, G, H, J, L, and M are all modeled representations of the relative position of the read head 1 (write head 9) with respect to the magnetic tape. Points AB, C, D, E,
The path connecting F, G, and H shows the case of operation using the conventional first positioning control method, and points A, B, C, D, and L.
, M is the conventional second positioning control method, and there is slippage between the capstan and the magnetic tape.
This shows a case where the light head position has returned too far.

and points A, B, C, D, J, and point A.

The route connecting B, C, D, L, and M shows the case of this embodiment.

Now, suppose that an overrun is detected at point A while the overrun detection circuit 4 is writing to the Nth block area 23, the traveling control circuit 10 detects an overrun in the servo amplifier 1.
1, the forward signal 16 to be sent to point 1 is turned off, the capstan motor 12 is stopped, and then the reverse signal 17 is turned on, and the tacho pulse counting circuit 14 measures the output pulses of the optical tachometer 13 from the second point A through B and C to the point. Return while counting the number of.

Next, at one point, the reverse signal 17 is turned off, and if there is no slippage between the capstan and the magnetic tape, the capstan motor 12 stops at one point.

Next, the forward signal 16 is turned on at one point, the magnetic tape is brought to that point, and the data on the magnetic tape is read.

At this time, the recording state check circuit 5 checks the presence or absence of a signal from the read circuit 3 and outputs the result to the command control circuit 6. Since no data has been written on the magnetic tape at point K, the instruction control circuit 6 immediately operates the write circuit 8 to rewrite the Nth block area 23.

At this point, there was slippage between the capstan and the tape, and the light head position returned too far, causing points A, B, and C in Figure 2.
, D, L, M, the instruction control circuit 6
waits until there is no more data on the magnetic tape (at the position of the point in FIG. 2) according to the output signal of the recording status check circuit 5, and then operates the write circuit 8 to write the Nth block area 2.
Rewrite 3.

In this way, after repositioning the head, rewriting is performed after checking the recording state on the magnetic tape.
Unlike the second control method, there is no need to return to the previous block, and unlike the second conventional control method, there is no risk of erasing the trailing edge of the previous block.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, as described in detail, by checking the recording state of the magnetic tape for overruns during a write operation, the magnetic tape can be returned to the previous block that has already been written. This has the effect that accurate positioning can be achieved without deteriorating the throughput due to this, and there is no possibility of erasing part of the previous block that has already been written.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a model diagram showing the operation of the embodiment of the present invention. Explanation of symbols of main parts 1... Read head 4... Overrun detection circuit 5... Recording status check circuit 9... Write head 10...・・Travel control circuit

Claims (1)

[Claims] (1) A positioning control method in a streaming mode magnetic tape device that repositions the magnetic tape relative to the head when a command overrun is detected while writing a data block to a predetermined position on the magnetic tape, means for repositioning the magnetic tape to the position of the next data block to be written in response to the command overrun detection; and means for checking the recording state of data at that position on the magnetic tape after the repositioning. When no data is written to this position, the data block is written to the next position, and when data is written, the magnetic tape is repositioned to the unwritten position and moved to the next position. A positioning control method characterized by controlling the writing of data blocks.