Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1997-03-27
2001-08-28
Baker, Stephen M. (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
Reexamination Certificate
active
06282688
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a recording apparatus capable of varying the length of identification (ID) data of recording data in a bit unit and/or improving reliability of data transfer between a host computer and a recording medium by use of an error detection/error correction function.
2. Description of the Related Art
Technique relating to conventional recording apparatuses such as a magnetic disk control apparatus is described, for example, in the instruction manual of “HD64950S” (a hard disk controller of Hitachi, Ltd.). Thereby, identification (ID) data is generated at the time of disk formatting and contains cylinder address data, head address data, sector address data and flag data. The length of each data is set and fixed in a byte unit. At the time of search for a sector, ID data of an object sector and read ID data are compared with each other, and whether or not the sector corresponding to the read ID data is the object sector is judged on the basis of coincidence or non-coincidence of the ID data as a whole.
However, the prior art technique described above does not much take into consideration the reduction of a storage region for storing the ID data which reduction is required with a greater capacity and higher performance of a magnetic disk apparatus, or in other words, optimization in accordance with a necessary data quantity, and diversification of ID data searching functions.
The conventional recording apparatus is equipped with a error detecting and error correcting function for data transfer between a recording medium and a data buffer but does not have such a function for data transfer between a host computer and the data buffer. For this reason, even when erroneous data is transferred from the host computer to the data buffer, the error cannot be detected and corrected, so that reliability of the entire system inclusive of the disk apparatus tends to remarkably drop.
Furthermore, a check symbol added to data to be recorded is only one kind. Therefore, when any-error occurs in the check symbol itself or when the check symbol becomes non-reproducible, the data is likely to be judged as wrong or the error correction cannot be made correctly even though the data itself does not contain any error.
Data is recorded dividedly in each sector as a recording unit, and reproduction of the data is made in this sector unit. In this case, no problem occurs if the data of only one sector is reproduced but when a plurality of sectors are reproduced continuously, the following problem occurs. The data reproduced from a recording medium become sequentially the object of error detection processing in an error detection/correction circuit (ECC) and the error correction processing is executed if any error exists. When the error is detected in the data reproduced from any of the sectors other than the last sector, the data from a next sector is reproduced while the error correcting processing is being made for this sector data, so that the error detection processing cannot be made for the next sector data. For this reason, conventionally, after one rotation of the disk is waited for, the next sector data is reproduced and is subjected to the error detection processing. According to this method, however, the data read-out operation is retarded by the time corresponding to one rotation of the disk, so that data transfer performance is deteriorated drastically.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a disk apparatus capable of varying a memory region of an identification (ID) data.
It is another object of the present invention to provide a disk apparatus capable of improving reliability of data not only for data transfer between a recording medium and a data buffer but also for data transfer between a host computer and the data buffer.
It is still another object of the present invention to provide a disk apparatus capable of improving reliability for an inspection symbol.
It is still another object of the present invention to provide a disk apparatus capable of preventing the drop of transfer performance occurring due to the error of a data during a read operation of a plurality of continuous sectors.
To accomplish the objects described above, a magnetic disk control apparatus for judging whether a given sector is a requested sector, from the ID data read out from a disk includes a first setting unit for variably setting the length of a memory region of the ID data in a bit or byte unit, an output unit for outputting the ID data in a set length to the disk, an input unit for inputting the read ID data, and a comparison unit for comparing ID data having variable lengths.
In a disk control apparatus for judging-whether or not a given sector is a requested data from the ID data read out from a disk, a memory region of each of the cylinder address data, head address data, sector address data and flag data is set by a first setting unit in a bit or byte unit in an optimum length for ID data of the disk apparatus. The ID data is outputted in a set length by an output unit. At the time of data input/output, an input unit inputs the ID data read out from the disk, and a comparison unit compares the ID data having a variable length.
To accomplish another object of the invention described above, the present invention includes a first error detection/correction (ECC) unit of data for generating check symbols for data in order to detect and record an error of the data during data transfer between a host computer and a data buffer, and a second ECC unit for generating check symbols for data to be recorded and for detecting an error of reproduced data during data transfer between a recording medium and the data buffer.
To accomplish still another object of the invention described above, the present invention includes a transfer unit for writing data from a host computer into a data buffer and reading the data from the data buffer and transferring it to the host computer, a read unit for reading the data from the data buffer for the purpose of recording, first and second ECC units for generating first and second check symbols for the data, from the data read out from the data buffer, a generation unit for adding the first and second check symbols to the data read out from the data buffer and using them as recording data on a recording medium, a write unit for writing only data, among the reproduced data having the first and second check symbols added thereto and reproduced from the recording medium, into the data buffer, a third ECC unit for detecting an error of the data from the data among the reproduction data and from the first check symbols, and a fourth ECC unit for detecting an error of the data from the data among the reproduced data and from the first check symbol.
Furthermore, the present invention includes a write unit for writing only the data, among the sector data obtained by adding a check symbol to the data and reproduced from a recording medium in a sector unit, into a data buffer, first and second ECC units for detecting and correcting an error of the sector data, and a transfer unit for alternately allotting and transferring alternately the data to the first and second ECC units for each sector data.
Only the data among the data which is transferred from the host computer and has the check symbol is transferred to, and stored in, the data buffer, and is then transferred with the check symbol to the first ECC unit. The first ECC unit executes the error detection of the data from the check symbol-and when any error is detected, the data stored in the data buffer can be corrected. When the data written into this data buffer is transferred to the host computer, the first ECC unit generates the check symbol for the data and adds it to the data, and the data after the addition of the check symbol can be transferred to the host computer.
When the data is transferred from the data buffer to the recording medium, the check symbols for the data are separately generated by the first and
Isono Soichi
Karasawa Noriyuki
Kojima Akira
Miyazawa Syoichi
Oeda Takashi
Antonelli Terry Stout & Kraus LLP
Baker Stephen M.
Hitachi , Ltd.
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