JPH02306473A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce the load of a host computer by preparing the address information on a defective data block and a substitute data block and carrying on the due process based on these address information when an error is detected out of the data read out by the host computer. CONSTITUTION:A track TRKb includes the data block address information DBA which shows the position of a data block on a magnetic disk and a substitute data block ADB which shows the substitute for a defective track TRKa of the data block. If the defective information on a desired data block is set in a read mode, the due process is carried on with high efficiency according to a fact whether the not used information on the substitute data block ADB pointed by the information DBA is not used yet or not. As a result, the load of a host computer is reduced at occurrence of an error.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a system for automatically converting other data blocks that function normally in subsequent accesses when a specific data block on a magnetic disk is determined to be defective. The present invention relates to a magnetic disk device that can be accessed manually.

[Prior Art] In order to improve the added value of recent magnetic disk devices and to unify system interfaces for interconnecting with other devices, small computer system interfaces (SCS : S
mall computer system
rface) is available.

FIG. 5 is a block diagram showing the general configuration of this type of magnetic disk device. The CPU (central processing unit) 1 performs various data processing required by the magnetic disk device and input/output processing necessary for accessing the magnetic disk (not shown), and processes various data via the bus 2. , a drive circuit 4 for driving a magnetic disk, and an input/output interface 5. The input/output interface 5 is connected to a host computer 7 via an external bus 6.

In such a configuration, when the post computer 7 reads data from a certain track on the magnetic disk and an error check detects a read error caused by a bad data block, the host computer 7 performs the following processing. must be carried out. (a) interrupt processing; (b) issue an instruction to obtain the address of the bad data block; and (c) update a data table for the bad data block and its replacement data blocks. Issue. When the host computer 7 needs to access the defective data block after executing the above processing, it refers to the data table and accesses an alternative data block.

[Problems to be Solved by the Invention] As described above, in the conventional technology, when a bad data block is detected when accessing a data block on a magnetic disk, that is, when a continuous error occurs, the host The problem is that the processing that the computer executes is complex and puts a heavy burden on it.

This invention was made in view of the above circumstances, and even if an error occurs when a host computer accesses a data block of a magnetic disk device, it can be corrected without increasing the load on the host computer. It is an object of the present invention to provide a magnetic disk device that can handle the problem efficiently.

"Means for Solving the Problems" In order to solve the above-mentioned problems, the magnetic disk device of the present invention provides that when an error is detected in data successively continued from a target data block, defect information indicating that the data block is defective, address information indicating the alternative data block, and the alternative data block.
A magnetic disk that has a recording area that stores usage flag information indicating whether or not the block is used, and if the defective information of the target data block is set in the case of continuous output, alternative data indicated by the address information. - Check the use flag information of the block, and if the use flag information indicates unused, prohibit reading of the data block, access and write to the alternative data block, and set the use flag. It is characterized by comprising an alternative processing means for rewriting the contents of the information to the usage state.

[Operation] In the magnetic disk device of the present invention, when the above-mentioned defective information of the target data block is set at the time of reading, the above-mentioned unused information of the alternative data block indicated by the address information is unused. Processing is performed efficiently depending on whether or not there is an error, and the host
Reduce the load on your computer.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

Figure 2 shows three types of tracks TRK on a magnetic disk.
FIG. 3A is a diagram showing the configuration of TRKb and TRKc. Track TRKa contains data block address information D indicating the location of the data block on the magnetic disk.
BA and a defective data block EDB indicating that the data block is defective. Truck TR
Kb includes data block address information DBA indicating the location of the data block on the magnetic disk, and alternative data indicating that the track TRK a of the data block is to be used as a substitute when the track TRK a of the data block is defective.・Block ADB. As shown in detail in FIG. 1, the track TRKc is a special data block that records each piece of information in the address information table AITB, and the number of pieces of address information written in the address information table AITB is The address information written number NWAI' indicating the address information, the defective data block address information EDBA indicating the address of the defective data block, and the alternative data block address indicating the address of an alternative data block that replaces the defective data block. Address information A
DBA and unused flag data NUFD indicating whether the alternative data block is unused are set.

The number of sets of defective data block address information EDBA, alternative data block address information ADBA, and unused flag data NUF is equal to the number of addresses written NUF.
Shown in WA r.

Next, as an explanation of the operation, each process executed by the CPU 1 in the above configuration will be explained.

(a) Data Block Read Process FIG. 3 is a flowchart illustrating the data block read process. In step Sl, a track TRKa on the magnetic disk in which the target data block to be accessed is recorded is detected. In step S2, data block address information DBA of the data block is detected. In step S3, the content (iD) of the data block 7 address information DBA is defective (BAD).
), that is, iD≠BAI), the process goes to step S4. In step S4, data is read. In step S5, it is determined whether or not there is an error in the read data. If there is an error, step S
6, the content of the data block address information DBA of the data block is set to BAD, and in step S7, +1 is added to the address information write number NWAI, and the defective data block address information EDBA is written in the address information table AI'rB. , and alternative data block address information ADBA are added, and unused flag data NUF'D is set, that is, turned on, in step S8. In step S9, the read error is processed and the process ends. Thereafter, even if the host computer 7 goes to read the data block, the answer in step S3 is YES, so the address information table AITB is searched in step SIO. In step Sll, it is determined whether there is defective data block address information EDBΔ for the data block. If YES, it is determined in step S12 whether or not the unused flag data NUFD is set. Here, the answer is YES, so read error processing is performed again in step S9, and the process ends. This flow is repeated as long as the data block address information DBA is BAD. If the unused flag data NUFD is not set in step S12,
In step SI3, a track to be substituted is detected according to the substitute data block address information ADBA, and the process returns to step S2. Further, when it is determined in step S11 that there is no defective data block address information EDBA for the data block, step S14
Processing is executed to assume that the target block is not detected at , and the process ends.

If the answer is NO in step S5, data transfer is performed in step S15 and the process ends.

(b) Data Block Write Process FIG. 4 is a flowchart showing the data block write process. In step 916, the target track is detected. In step S17, the data of the track is
Examine block address information DBA. Step 81
When the content of the data block address information DBA is BAD in step S19, the number of written addresses NWAI in the address information table AITB shown in FIG. Search data block address information ADBA. When it is determined in step S20 that the defective data block address information EDBA is present, the unused flag data NUFD is set off in step S21. Step 92
2, alternative data block address information ADB
According to A, the alternative destination track is detected and the process returns to step S17. If the alternative destination track is not BAD, that is, if it is determined that it is normal, the answer in step 818 becomes NO, data is written in step S23, and the process ends. If the answer is NO in step S18, data writing is executed in step S23, and the process ends. Further, when the result in step S20 is NO, a process in which the target data block is not found is executed in step S24, and the process ends.

(c) Alternative data block A D B + for data block EDB with defective data read processing after writing data to the alternative data block ADH one or more times;
If data has been written 11 times or more, BAD has been written in the data block address information DBA of the track, and the address information table AIT
Off is written in the unused flag data NUFD of B. In this state, when the host computer 7 attempts to read the data block, step Sl shown in the flowchart of FIG.

S2. S3. SIO, Sl 1. S12. S13. S2
By executing S 3 , S 4 , S 5 and S15, the alternative data block ADH is accessed and the data transfer is completed normally. When a new error occurs in step S5, as explained in (a), the data block address information DBA of the alternative data block ADB is set to BAD, and the new alternative block is accessed to complete the data transfer. .

In addition, in this invention, the address information table AI
It is not necessary that each column of the TB be limited to that of the above embodiment, and the information recording medium and format need not be limited to the track format, but may be other formats. Furthermore, the information retrieval means may also be of other formats. In either case, the same effects as in the above embodiments are achieved.

[Effects of the Invention] As explained above, according to the present invention, when an error is detected in data read by a host computer from a data block, information regarding the defective data block and alternative data block is automatically determined. address information is prepared, and processing can be continued according to these address information, resulting in the following effects.

(a) the host computer does not have to interrupt ongoing processing, (b) the host computer does not have to search again for the address of the bad data block, and (c) the host
The computer does not have to perform any replacement processing for bad data blocks.

Therefore, the load on the post computer is significantly reduced, and data transfer can be efficiently completed.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an address information table AITB in a magnetic disk device according to an embodiment of the present invention, FIG. 2 is a configuration diagram of data blocks formed on tracks of a magnetic disk, and FIGS. 3 and 4 is a flowchart explaining the operation of the magnetic disk device, and FIG. 5 is a block diagram of the magnetic disk device. l...CPU (central processing unit, control means), 3
...Memory, 7...Host computer, A
DH...Alternative data block, ADBA...
・・・Alternative data block address information, DBA・
...Data block address information, EDB...
...Bad data block, EI) BA...
・Bad data block address information, NtJPD・
...Unused flag data, NWA I...
・・Number of address information written, TRKa=TRKc・・
····truck.

Claims (1)

[Claims] When an error is detected in data read from a target data block, defect information indicating that the target data block is defective, address information indicating an alternative data block, and A magnetic disk having a recording area storing use flag information indicating whether or not the alternative data block is used, and when the defect information of the target data block is set in the case of reading, the address information is specified Check the usage flag information of the alternative data block to be used, and if the usage flag information indicates unused, the data block is
In addition to prohibiting reading of the block, the corresponding alternative data
What is claimed is: 1. A magnetic disk device comprising: alternative processing means for accessing and writing a block and rewriting the contents of the usage flag information to a usage state.