JPH0417458B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a fixed-length block magnetic disk drive, and in particular to a method for controlling software when data read from the magnetic disk drive by a magnetic disk control device can be guaranteed. The present invention relates to a replacement block allocation method for moving data from a defective block to a replacement block without intervention.

(b) Prior Art and Problems Due to manufacturing problems, magnetic disk media used in magnetic disk devices have defects on the surface of the medium, which may cause errors when reading recorded data. As shown in Figure 1, the sector format in a fixed-length block magnetic disk device is such that an ID section for recording index information and data are recorded in each sector that divides each track.
A DATA section is provided. If there is an error in the information in the ID section due to a defect in the medium, or if a correctable error occurs in the DATA section, the data can be guaranteed. A spare area is provided in a part of the block, and the data is transferred to the spare block of the area.

In a conventional fixed-length block magnetic disk device, replacement blocks are allocated using a format differential subcommand of a software locate command. When the subcommand is given to the magnetic disk control device from the host device, it operates as described below.

Search for an unallocated spare block starting from the spare area with the shortest seek (operation to position the magnetic head on the target track) time.

After an unallocated block in the spare area is found, the ID part of the defective block is written with a defect flag attached.

Next, read the ID part of the defective block. If an error occurs during reading, try writing again at a position shifted by several tens to hundreds of bytes.

Try reading the ID part of the defective block again.
If there is an error, shift it again by several tens to hundreds of bytes.
Write the ID part.

Furthermore, if the ID section is read and an error still occurs, an error report is sent to the host device.

There is no error in the operation of ~ and there is no defective block.
If the reading of the ID part is successful, the replacement block
Write to the ID section with the replacement block flag and assigned flag.

This completes the replacement block allocation process, but
Writing the data written in the DATA section of a defective block to the DATA section of a replacement block is done by software, which has the drawback of increasing the software load.

(c) Object of the Invention The object of the present invention is to eliminate the above-mentioned drawbacks, and when allocating a replacement block, the magnetic disk control device saves the data of the defective block to the buffer memory without using software, so that the data of the replacement block is saved. The object of the present invention is to provide a spare block allocation method that reduces the load on software by writing the data saved in the buffer memory into the DATA section of the spare block after the allocation process is completed.

(d) Structure of the Invention The structure of the present invention is a magnetic disk control device that controls a fixed-length block magnetic disk device.
A buffer memory is provided to save the data written in the data section of the defective block when a command sent from the host device instructing replacement block allocation is received, and based on the command instructing replacement block allocation, the buffer memory is saved. Data is saved from the data section of a defective block, and when the allocation of a replacement block to the defective block is completed, the data saved in the buffer memory is written into the data section of the replacement block.

(e) Embodiment of the Invention FIG. 2 shows an example of the configuration of a magnetic disk subsystem illustrating an embodiment of the invention. The magnetic disk control device 1 is connected to the magnetic disk device 3 via the magnetic disk control adapter 2 according to a command from the host device.
or 4 to write/read data to/from the magnetic disks of the magnetic disk devices 3 and 4. Third
The figure shows an example of a track for a cylinder. For example, suppose that the block indicated by A is defective and an error occurs in the ID section or DATA section. If block B in the replacement area is unallocated, the operation will be as described below.

(1) A format defective subcommand is issued to the magnetic disk controller 1 from the host device to designate block A as defective.

(2) The magnetic disk control device 1 is
Read the DATA section into buffer memory 5. At this time, if a correctable error occurs, it is corrected and read, but if it is uncorrectable, it is processed in the same manner as before and the present invention is not applied.

(3) Find an unallocated block in the spare area with the shortest seek time. In this example, it is B.

(4) Write the ID part of defective block A with a defect flag attached.

(5) Read the ID part of defective block A. If an error occurs, the ID part is written again at a position shifted by several tens to hundreds of bytes.

(6) Try reading the ID section again. If there is an error, the ID part is written with a further shift of several tens to hundreds of bytes.

(7) Try reading out the ID section again. If an error still occurs, the error is reported to the host device.

(8) If the reading of the ID part is completed without any error in the operations (4) to (7), write the ID part of the spare block B with the spare block flag and the allocated flag attached.

(9) Write the data read into the buffer memory 5 in (2) into the DATA section of the replacement block B.

(f) Effect of the Invention As explained above, the present invention uses software to enable the magnetic disk control device to independently execute the data recorded in the data section after the allocation of replacement blocks without the intervention of software. The load on clothing can be reduced.

[Brief explanation of drawings]

Figure 1 shows the sector format, Figure 2 shows the sector format.
The figure shows a magnetic disk illustrating one embodiment of the present invention.
FIG. 3 is a diagram showing an example of the configuration of a subsystem. FIG. 3 is a diagram showing an example of a track of a certain cylinder. 1 is a magnetic disk control device, 2 is a magnetic disk control adapter, 3 and 4 are magnetic disk devices, and 5 is a buffer memory.

Claims (1)

[Scope of Claims] 1. In a magnetic disk control device that controls a fixed-length block magnetic disk device, when receiving a command sent from a host device instructing replacement block allocation, A buffer memory is provided to save the data in the defective block, and based on the command instructing the replacement block allocation, the data is saved from the data section of the defective block to the buffer memory, and when the allocation of the replacement block to the defective block is completed, the data is transferred to the buffer memory. A spare block allocation method characterized in that the saved data is written into the data section of the spare block.