JPS58211257A - Write controlling system of magnetic disk device - Google Patents

Abstract

PURPOSE:To protect exactly a data which is written already, by providing a flag part provided with a write inhibiting bit to each sector, on a data part, referring to this write inhibiting bit, and deciding whether write is allowable or not. CONSTITUTION:First of all, a flag part 6 of a magnetic disk 2 is read out to a read buffer R2. Subsequently, a sector designated by this command is compared with a write inhibiting bit corresponding to a sector of a flag data read out in the buffer R2. When this write inhibiting bit is off, a data which adds a check bit to a write data from a channel 4 is inputted to a write buffer W2. Subsequently, an operation for writing a data of the buffer W2 in a sector of the disk 2 is executed. On the other hand, when the write inhibiting bit is on, a data part write inhibiting signal is generated, and this write command is made ineffective.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a data write control method in a sector-type magnetic disk drive, and in particular to a data write control method for an address where data has already been written to the data section of the same address. The present invention relates to a write control method in which, when an access is executed, the device side reads attributes related to the address from a flag section, refers to the bit contents, and determines whether or not a write access is to be performed.

(2) Conventional technology and problems Conventionally, the write control method for magnetic disk devices used a protection switch added to the hardware, but this method requires operator intervention, which can lead to mistakes in setting the machine number, etc. There were drawbacks.

(3) Purpose of the Invention An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a method for reliably protecting data already written on a magnetic disk medium.

(4) Structure of the Invention The object is to provide a flag section with a write inhibit bit in each sector in a data section in a magnetic disk device connected to a central processing unit via a channel, and to receive a write instruction from the channel. This is achieved by a write control method for a magnetic disk device characterized by providing means for determining whether or not writing is possible by referring to write inhibition bits corresponding to μ.

(5) Examples of the invention The present invention will be described in detail below using the drawings.

FIG. 1 is a functional block diagram showing one embodiment of the present invention.

7-V in the figure: 1 is the magnetic disk control section, 2 is the magnetic disk, 3 is the disk control, 4 is the channel, 5 is the command analysis, 6 is the flag section, and 7 is the data section.

8 is an ECC generator, 9 is an ECC checker.

10 is a collector, w, and w2 are write buffers.

R1* R2 is a read buffer.

FIG. 2 shows the structure of flags and data in multiple sectors (one cylinder or one device) showing one embodiment of the present invention. (A common flag section is provided for multiple sectors, and a write inhibition bit is assigned to each sector.) The operation of each command to the magnetic disk device 2 in a sector type magnetic disk device is (1) In the case of a read command, the conventional read Similar to the command, data is read from the magnetic disk 2 to the read buffer R2, and the ECC checker 9
The presence or absence of a data error is detected at , and if the error is correctable, a syndrome is created, corrected at collector IOK, and correct data is sent to channel 4 via read buffer R1'.

(1) In the case of a write flag command Flag data specified by the command is written to the flag section 6 of the magnetic disk 2, and the write inhibit bit for each sector is set (on) or canceled (off).

(Tsukuda) In the case of a write command, first read the flag part 6 of the magnetic disk 2 to the read buffer R2 at timing TI, and then read the flag section 6 of the magnetic disk 2 to the read buffer R2, and then read the flag part 6 of the magnetic disk 2 corresponding to the sector 1 specified by the command and the sector 1 of the flag data read to the read buffer R2. A comparison is made with write inhibition bit i. If the write inhibit bit 1 is off, the same write operation as before at timing T2, that is, channel 4
The data obtained by adding the check bit created by the ECC generator 8 to the write data from the above is put into the write buffer W2, and then the data in the write buffer W2 is transferred to sector 1, which is a predetermined position of the magnetic disk 2, as shown in FIG. Perform a write operation in the format. On the other hand, if the write inhibit bit 1 is on, a data section write inhibit signal is created to invalidate the write command.

(6) As described in detail, according to the present invention, rewriting of a specific block (sector) in a continuous data space as an external storage device (magnetic disk, etc.) can be reliably and easily performed. This has the effect of improving the data protection function.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing one embodiment of the present invention. FIG. 2 shows the structure of flags and data in multiple sectors (one cylinder or one device) showing one embodiment of the present invention. Explanation of symbols: iF'i magnetic disk control section, 2 is a magnetic disk, 3 is a disk control, 4 is a channel, 5 is a command analysis, 6 is a flag section, 7 is a data section. 8 is an ECC generator, 9 is an ECC checker. 1 (l collector + Wl, W2 is a write buffer. R1+R2 is a read buffer.

Claims (1)

[Claims] In a magnetic disk device connected to a central processing unit via a channel, a flag section with a write inhibit bit is provided for each sector in the data section, and the write inhibit bit is set in response to a write instruction from the channel. 1. A write control method for a magnetic disk device, comprising means for referring to it and determining whether writing is possible.