JPH0799608B2 - Track emulation method for magnetic disk unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention relates to a track emulation system of a magnetic disk device that makes track capacities compatible between a new model and an old model having different track capacities. ECC by using
The purpose is to provide a simple and highly reliable track emulation method that can correct errors by using the new model and does not require the addition of new circuits. Write or read data is transferred between the host device and the disk storage mechanism according to the track format. The value of the segment number included in the count section is detected when the count section of the track format is transferred. Further, since the key part and the data part are repeatedly transferred through the gap after the transfer of the count part, the gap length and the length of the transfer target part are sequentially added to the value of the detected segment number. When it is determined that the track capacity of the old model has been reached, the fact is reported to the host device.

[Industrial field of application] The present invention provides a magnetic disk which is compatible with the track capacity when a small capacity old magnetic disk apparatus connected to a host apparatus is replaced with a new large capacity magnetic disk apparatus. The present invention relates to an emulation method of a disk device.

In various computer systems with a magnetic disk device connected as an external storage device, if you want to increase the storage capacity or if the previous magnetic disk device fails, connect it to the CPU as a higher-level device. The existing magnetic disk device may be replaced with a new magnetic disk device having a large capacity.

In this way, when the magnetic disk device is changed to a new large-capacity model, the host device still regards it as an old small-capacity magnetic disk device for writing and reading data, and therefore, a new large-capacity magnetic disk device. The so-called track emulation is required to match the track capacity of the above-mentioned track capacity of the old small capacity magnetic disk drive.

[Prior Art] FIG. 5 shows a computer system in which a conventional magnetic disk device is connected as an external device.

In FIG. 5, reference numeral 10 is a host device having a CPU, and a magnetic disk device 12 is connected to the host device 10. The magnetic disk device 12 includes a control adapter 36 and a plurality of storage mechanisms 14a, 14b, ... Having a magnetic disk as a storage medium.

This magnetic disk device 12 is a large-capacity device newly connected to the old model by replacement, but since the control format of the host device 10 has not been changed, the host device 10 still has a small old track capacity before replacement. Since data writing or reading is performed by considering it as a magnetic disk device, the control adapter 36 performs track emulation for adjusting the track capacity of the new model to that of the old model.

As a track emulation by the control adapter 36, a technique using a track counter has been conventionally known.

Figure 6 shows the track used for track emulation.
3 shows a track format with a counter. Here, as shown in FIG. 6, the track counter is a new track count added after ECC (error correction code) in the count section of the track format. , The number of recording bytes up to the recording position when recording is performed in the track format of an old small capacity magnetic disk device.

FIG. 7 shows the structure of a conventional control adapter 36 for performing track emulation using the value of the track counter added after the counting section shown in FIG.

The control adapter 36 shown in FIG. 7 includes a VFO circuit 26 for writing or reading data in synchronization with the servo clock obtained from the servo head between the storage mechanisms 14a, 14b, ... Of the disk storage unit. , A serial-parallel conversion circuit 28 for performing serial-parallel mutual conversion of write or read data,
A data transfer buffer circuit 30 for transferring write or read data to and from the host device 10 and an ECC circuit 32 for detecting and correcting an error in read data are provided, and a track counter is newly added for track emulation. Circuit 38
And a gap control circuit 40 is provided.

That is, when data is written or read by the higher-level device 10, the sixth
When the data transfer buffer circuit 30 receives and transfers the count section of the track format shown in the figure, the value of the track counter added to the count section is fetched and set in the track counter circuit 38 as an initial value. Subsequently, the track counter circuit 38 adds the length of the old model gap G2 output from the gap control circuit 40 to the fetched initial value, and after adding the length of the key part in the next transfer of the key part. Gap G2 following the data part after adding the length of the gap part G2 again and further adding the length of the data part in the transfer of the data part
And the length of the transfer target part (key part or data part) and the gap length are repeated.

When the count value of the track counter circuit 38 reaches the track capacity of the magnetic disk device of the old model, the track
An index is generated, and this is notified to the host device 10 to make the track capacities compatible.

[Problems to be Solved by the Invention] However, in such a conventional track emulation system for achieving compatibility of track capacities,
Since ECC is not added to the track count value provided in the count section, if the track count value could not be read accurately due to the presence of a defect on the disk medium, the parity check of the track count is used to If an error is reported to the device or if a parity error does not occur, an incorrect count value will be set in the track counter circuit, and the subsequent count operation will be messed up, leading to a lack of reliability. .

Furthermore, the track counter circuit has to be added to the control adapter, which causes a problem that the circuit becomes complicated and the cost increases.

The present invention has been made in view of such conventional problems, and by using the value of the segment number already written in the count section, error correction by ECC is possible and a new circuit is added. It is an object of the present invention to provide a simple and highly reliable magnetic disk device emulation method that does not require the above.

[Means for Solving Problems] FIG. 1 is a diagram illustrating the principle of the emulation method of the present invention.

In FIG. 1 (a), the host device 10 controls a small-capacity magnetic disk device that is an old model, but a large-capacity magnetic disk device 12 that is a new model in place of the old model is connected to the host device 10. When data writing or reading is performed between the device 10 and the large-capacity magnetic disk device 12, track emulation is performed to make the track capacities compatible.

The control adapter of the magnetic disk device 12 is shown in FIG.
Higher-order device according to the track format of the old model shown in
Data transfer control means 18 for controlling transfer of write data or read data is provided between 10 and a storage mechanism 14 of a large-capacity magnetic disk device 12.

When the data transfer control means 18 transfers the data of the count portion in the track format, the detecting means 18 detects the value of the segment number included in the count portion.

Then, every time the data transfer control means 16 sequentially performs the data transfer of the key portion and the data portion through the gap G2, the segment number value detected by the detecting means 18 is set to the value of the old model gap G2. The length and the length of the transfer target part (key part or data part) are added by the adding means 20.

Each time the adding means 20 adds the value of the length of the gap G2 or the length of the transfer target portion, the added value is determined by the track capacity determining means 22 whether or not the track capacity of the old model has been reached. When it is determined that the track capacity has been reached, a track index is generated and the fact is reported to the upper level device 10.

Here, the detection means 18, the addition means 20, and the track capacity determination means 22 of the control adapter are achieved as one of the processing sequences of the processor circuit dedicated to the write / read control provided in the control adapter, and a special circuit needs to be provided. There is no.

[Operation] The segment number of the count section represents the number of segments up to the segment position where the count section is, when the track is divided into 32 byte segments.

For this reason, the segment number included in the count section is read during the data transfer of the count section, and the gap length in the track format of the old model is sequentially added to the value of this segment number together with the length of the key section and the data section. To do. For this reason, the track count value of the old model is obtained in real time by the data transfer in the data writing or reading of the new model, and when the track count value reaches the track capacity of the old model, the track index (pseudo index) Is generated and reported to the host device, the track capacity can be compatible between the new model and the old model.

In addition, since the segment number is located before the ECC of the counting part, even if the segment number cannot be read correctly due to a defect in the disk medium, etc., the correct segment number value can be obtained by error correction based on the ECC. Therefore, it is possible to accurately detect the value of the track count for making the track capacities compatible, and it is possible to obtain high reliability.

Furthermore, since recent control adapters have a built-in processor circuit dedicated to writing and control, segment number detection, gap length addition, and whether the track capacity of the old model has been reached or not. The determination can be realized by incorporating it as one of the control sequences of this processor circuit, and since it is not necessary to add a special circuit, the circuit configuration does not become complicated and the cost can be reduced.

[Embodiment] FIG. 2 is an explanatory view showing an embodiment of a magnetic disk device for realizing the track emulation method of the present invention.

In FIG. 2, the magnetic disk device 12 is a large-capacity device that is newly connected to the host device, and the track capacity is increasing compared to the old model.

The magnetic disk device 12 includes a control adapter 24 and a disk storage unit.
Composed of 25. The disk storage unit 25 is provided with a plurality of storage mechanisms 14a, 14b, ... Having a magnetic disk as a storage medium.

On the other hand, the control adapter 24 has a VFO circuit for reading or writing data to the storage mechanisms 14a, 14b, ... Based on the servo clock from the servo head on the side of the disk storage unit 25, as in the conventional device. 26, a serial / parallel conversion circuit 28 that performs mutual conversion between serial data and parallel data, a data transfer buffer circuit 30 that transfers write data or read data between a host device (not shown), and read data ECC to detect and fix errors in
A circuit 32 is provided. Further, the control adapter 24 is provided with a dedicated processor circuit 34 for performing data write control and data read control between the host device and the magnetic disk device 12, and the VFO based on the control sequence of the processor control circuit 34 is provided. Circuit 26, serial / parallel conversion circuit 28,
The data transfer buffer circuit 30 and the ECC circuit 32 are controlled, and these constitute the data transfer control means 16 shown in the principle explanatory diagram of FIG.

The processor circuit 34 incorporates a track emulation processing function for making the track capacities of the large-capacity magnetic disk device 12 newly connected to the track capacities of the old model controlled by the higher-level device compatible. The track emulation by the processor circuit 34 is performed based on the value of the segment number included in the count part of the track format left in the data transfer buffer circuit 30 at the time of reading or writing the data.

FIG. 3 is an explanatory view showing the track format of the new model in the large-capacity magnetic disk device 12 shown in FIG. 2 and the track format of the old model controlled by the host device in comparison with each other. Track emulation is the gap G in the new model track format.
It effectively functions in the mode in which data is transferred from the count unit R1C following 3 '. Here, the count unit R1C has a data format shown by enlarging it with a dotted line, and each data has the following contents.

SD: Number of defect skips CN: Cell number (segment number) PA: Physical address F: Flag C: Cylinder information H: Head information RN: Record number KL: Key length DL: Data length ECC: Error correction code Among the various counting sections R1C, the cell number CN is used for track emulation of the present invention, and the cell number CN indicates the segment position of the counting section R1C when the track is divided into 32 byte segments, for example. Represents a segment number.

Therefore, in the processor circuit 34 of the embodiment shown in FIG. 2, when the data writing or the data reading is performed under the control of the processor circuit 34, the data transfer buffer circuit 30 transfers the track format count section. From the cell number CN of the count part remaining in the data transfer buffer 30 in the control adapter 24 when
Read the number, add the length of the gap G2 of the old model and the length of each transfer target part of the key part R1 K and the data part R1 D that are transferred subsequently to the count part R1 C to this segment number, and add this When the result reaches the track capacity of the old model, a pseudo index is generated as shown in FIG. 3 to report to the host device that the track capacity of the old model has been reached. In this manner, when the processor circuit 34 generates the pseudo index for compatibility of the track capacities,
The track area up to the regular track index is left as an unused area for compatibility with old models.

Further, when the track emulation control processing by the processor circuit 34 is arranged, the processor circuit 34 performs the following processing for track emulation.

(A) When the control adapter 24 transfers the data of the count section Ri C in the track format, the count section Ri C
Detection process for detecting the value of the segment number from the cell number CN included in C (however, i = 1, 2, ..., N).

(B) The control adapter 24 has a gap G2 'in the counting unit Ri C.
Each time the data of the key section Ri K and the data section Ri D is successively transferred via the, the segment number value detected in (A) above is added to the gap length value of the old model gap G2 and the transfer target section. Addition processing for adding the value of the length of (key part or data part).

(C) Every time the length of the gap G2 or the length of the transfer target portion is added in the addition processing of (B), it is determined whether or not the addition result has reached the track capacity of the old model, and the old model When determining that the track capacity has been reached, a pseudo index is generated and the effect is reported to the host device.

Of course, the track emulation processing in the processor circuit 34 shown in (A) to (C) above is performed in the same manner not only when reading data from the host device but also when writing data from the host device.

Next, the operation of the track emulation processing by the processor circuit 34 provided in the control adapter 24 of FIG. 2 will be described with reference to the flowchart of FIG.

When writing data to or reading data from the host device, the first count section R1 in the new model track format shown in FIG. 3 is read from the data transfer buffer circuit 30.
If the data transfer control of C is performed in step S1, the process proceeds to step S2, the segment number is read from the data transfer buffer 30, and in the next step S3, the value of the gap G2 in the track format of the old model is set to the segment number. Add.

In the next step S4, it is determined whether or not the segment number value obtained by adding the gap G2 in step S3 exceeds the track capacity of the old model, and if it does not exceed the track capacity of the old model, proceed to step S5. Controls data transfer of the key part R1K.

If the data transfer control of the key part R1K is performed in step S5, the length of the key part is added to the segment number in step S6, and it is determined in the next step S7 whether or not the track capacity of the old model is exceeded again. .

If the segment number value does not exceed the track capacity of the old model in step S7, the value of gap G2 is added to the segment number in the next step S8, and step S9 is executed again.
Check to see if the capacity of the old model has been exceeded. If the track capacity of the old model is not exceeded in step S9, the process proceeds to step S10 to control the data transfer of the data section R1 D, and in the next step S11, add the length of the data section R1 K to the segment number, and then repeat the step. In S12, it is determined whether or not the track capacity of the old model has been exceeded. If the track capacity of the old model is not exceeded in step S11, proceed to step S13, add the value of the gap G2 to the segment number, and in the next step S4 determine whether the track capacity of the old model is exceeded again. If it does not exceed the track capacity, the process proceeds to the data transfer control of the next count section R2C in S5, and in the same way, the length of the gap G2 and the length of the key section or the data section are added to the segment number in the same manner. The process of determining whether or not the track capacity of the old model has been exceeded is repeated.

On the other hand, if the segment number value exceeds the track capacity of the old model in any of steps S4, S7, S9, S12, and S14, proceed to any of steps S16 to S20 to generate a pseudo index. It will report the index fund indicating that the truck capacity of the old model has been reached to the upper device.

On the other hand, when data is read from the magnetic disk device 12 to the host device and the cell number CN of the count part cannot be read correctly due to a defect on the disk medium, the ECC added at the end of the count part Since error detection and correction are performed, the reliability of the segment number used for track emulation is guaranteed, and the compatibility with the track capacity of the old model can be accurately achieved.

Further, the track emulation of the present invention shown in the flowchart of FIG. 4 is provided as one of the control sequences of the read / write only processor circuit 34 provided in the control adapter 24 of the magnetic disk device 12. Since it is not necessary to add a special circuit such as a track counter circuit to the control adapter 24 as in the conventional case, the circuit configuration is simple and the cost can be reduced.

EFFECTS OF THE INVENTION As described above, according to the present invention, the track capacities are made compatible based on the segment number of the count section to which the ECC is added, so that the reliability is high and the processor of the control adapter is high. Since the track capacities are made compatible by the circuits, it is not necessary to add a special circuit, the circuit configuration is simple, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention, FIG. 2 is an explanatory view showing an embodiment of the present invention, FIG. 3 is an explanatory view of track formats of an old model and a new model used in the present invention, and FIG. FIG. 5 is a flow chart showing the track emulation processing of the present invention, FIG. 5 is an explanatory view of a conventional system, FIG. 6 is an explanatory view of a track format used in the conventional system, and FIG. 7 is an explanatory view of a conventional control adapter. is there. In the figure, 10: Host device 12: Magnetic disk device (new model) 14, 14a, 14b: Storage mechanism 16: Disk transfer control means 18: Detection means 20: Addition means 22: Track capacity determination means 24: Control adapter 25: Data storage unit 26: VFO circuit 28: Serial / parallel conversion circuit 30: Data transfer buffer circuit 32: ECC circuit 34: Processor circuit

Claims (1)

[Claims] 1. A high-capacity magnetic disk device (12) having different track capacities is connected to a host device (10) whose control target is a small-capacity magnetic disk device, and the high-capacity magnetic disk device and the high-capacity device In a track emulation method of a magnetic disk device, which makes track capacities compatible when writing or reading data with a disk device (12), the host device (according to the track format of the small capacity magnetic disk device Data transfer control means (1) for controlling transfer of write data or read data between the storage mechanism (14) of the large capacity magnetic disk device (12).
6) and; detection means (18) for detecting the value of the segment number included in the count part when the data transfer control means (16) transfers the data of the count part in the track format. The detecting means (1) every time the data transfer control means (16) successively performs data transfer of the key portion and the data portion, which successively repeat to the count portion via a predetermined gap area.
In the segment number value detected in 8), the gap area (G2) in the small-capacity magnetic disk unit
Addition means (2) and the value of the length of the transfer target part (2
Every time the value of the gap area (G2) or the transfer target portion is added by the adding means (20), it is determined whether or not the added value has reached the track capacity of the small capacity magnetic disk device. , Track capacity determination means (22) for reporting the fact to the host device (10) when it is determined that the track capacity has been reached
An emulation method for a magnetic disk device, which is characterized by including;