Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1999-11-17
2004-02-24
Decady, Albert (Department: 2784)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C360S053000
Reexamination Certificate
active
06697991
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic disk device having a controller, a drive and an interface unit related to SCSI (Small Computer System Interface) and, more particularly, to a data check circuit of a magnetic disk device for checking existence
on-existence of abnormality of data to be transferred in the magnetic disk device, a data check system of a magnetic disk device and a data checking method of a magnetic disk device.
2. Description of the Related Art
In a magnetic disk device in a personal computer or the like, data is transferred between a controller and a drive through an interface unit related to SCSI. In other words, “data writing” is conducted which is data transfer from an upper circuit in the controller to a lower circuit in the drive and “data reading” is conducted which is data transfer from the lower circuit to the upper circuit. Needed here, at such data transfer, is a check of the data in question for securing reliability of the data. Mechanisms realizing such a data check are a data check circuit of a magnetic disk device, a data check system of a magnetic disk device and a data checking method of a magnetic disk device according to the present invention.
In a data check circuit of a magnetic disk device of this kind (description will be here made of a conventional “data check circuit of a magnetic disk device” which also represents a “data check system of a magnetic disk device” and a “data checking method of a magnetic disk device”), conventionally, sending a parity code (parity signal) of data to be transferred onto a parity signal line provided together with an SCSI signal line (signal line for sending data based on SCSI) leads to a check of existence
on-existence of abnormality of the data in question.
In recent years, as the transfer rate of data to be transferred to/from a magnetic disk device has increased such that errors are more likely to occur, it becomes more difficult to ensure reliability of the data in question by only using a parity code.
The above-described conventional data check circuit of a magnetic disk device has the following problems.
The first problem is that in view of a recent increase in the transfer rate of data to be transferred to/from a magnetic disk device, it is difficult to ensure reliability of the data only with a parity code as mentioned above.
The second problem is that when an error occurs in data to be transferred to/from a magnetic disk device, correction of the data in question is impossible because a parity code has a data error detection function but lacks an error correction function.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a data check circuit of a magnetic disk device and a data checking method of a magnetic disk device which enable reliability of data to be sent and received (transferred) to be improved and an error occurring in the data in question to be corrected by the generation of an ECC (Error Correcting Code) from a data transmission side (at a controller at the time of data writing to a lower circuit in a drive and at the drive at the time of data reading into an upper circuit.in the controller) and sending of the same onto an existing parity signal line, and a check of the ECC at a data reception side (at the drive at the time of data writing and at the controller at the time of data reading).
Another object of the present invention is to provide a data check circuit of a magnetic disk device and a data checking method of a magnetic disk device enabling reliability of data to be transferred at the magnetic disk device to be more improved than that by the use of a parity code according to conventional art, thereby coping with a recent increase in a transfer rate at a magnetic disk device.
A further object.of the present invention is to provide a data check circuit of a magnetic disk device and a data checking method of a magnetic disk device enabling not only detection of an error in data to be transferred at the magnetic disk device but also correction of an error in data where the error is detected.
According to the first aspect of the invention, a data check device of a magnetic disk device, comprises
controller side data check means for conducting, at data writing, generation of an ECC for data sent from an upper circuit, sending of data through a data signal line and sending of the ECC onto a parity signal line, and at data reading, reception of data on the data signal line, reception of an ECC on the parity signal line, an ECC check based on the data and the ECC, correction of an error when the error is detected in the ECC check and sending of the data to the upper circuit; and
drive side data check means for conducting, at data writing, reception of data through the data signal line, reception of an ECC on the parity signal line, an ECC check based on the data and the ECC, correction of an error when the error is detected in the ECC check, and sending of the data to a lower circuit, and at data reading, generation of an ECC for data sent from the lower circuit, sending of the data onto the data signal line and sending of the ECC onto the parity signal line.
In the preferred construction, the controller side data check means comprises ECC generation means for generating the ECC based on data at data writing, ECC check means for conducting the ECC check at data reading, and ECC control means for correcting data based on the ECC check, and
the drive side data check means comprises ECC generation means for generating the ECC based on data at data reading, ECC check means for conducting the ECC check at data writing, and ECC control means for correcting data based on the ECC check.
In another preferred construction, the controller side data check means comprises ECC generation means for generating the ECC based on data at data writing, ECC check means for conducting the ECC check at data reading, ECC control means for correcting data based on the ECC check, and interface means for transmitting and receiving data to and from the drive side and transmitting data to the ECC generation means at data writing, and
the drive side data check means comprises ECC generation means for generating the ECC based on data at data reading, ECC check means for conducting the ECC check at data writing, ECC control means for correcting data based on the ECC check, and interface means for transmitting and receiving data to and from the controller side and transmitting data to the ECC generation means at data reading.
In another preferred construction, the controller side data check means comprises ECC generation means for generating the ECC based on data at data writing, ECC check means for conducting the ECC check at data reading, ECC control means for correcting data based on the ECC check, interface means for transmitting and receiving data to and from the drive side and transmitting data to the ECC generation means at data writing, and ECC memory means for storing an ECC generated by the ECC generation means and sending the ECC onto the parity signal line at data writing and receiving an ECC from the parity signal line and storing the ECC at data reading,
the ECC check means conducting an ECC check using an ECC stored in the ECC memory means and data received from the data signal line and outputting check results of the ECC check to the ECC control means at data reading, and
the drive side data check means comprises ECC generation means for generating the ECC based on data at data reading, ECC check means for conducting the ECC check at data writing, ECC control means for correcting data based on the ECC check, interface means for transmitting and receiving data to and from the controller side and transmitting data to the ECC generation means at data reading, and ECC memory means for receiving an ECC from the parity signal line and storing the ECC at data writing and storing an ECC generated by the ECC generation means and sending the ECC onto the parity signal line at data reading,
the ECC check means conducting an
Abraham Esaw
De'cady Albert
Foley & Lardner
NEC Corporation
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