JPS5819768A - Rotary type external storage device - Google Patents

Abstract

PURPOSE:To prevent the reduction of the system throughput, by extracting the signal including the data on the time when each rotary storage medium of the 1st and 2nd rotary type storage devices passes a specified position and carrying out the control of revolution based on the output of comparison. CONSTITUTION:The speed of revolution can be electrically controlled for the 1st and 2nd rotary storage devices 26 and 27. Index mark signal of each revolution is delivered from a detector 11 in the form of a signal which includes the data on the time when the rotary storage medium of the 1st device 26 passes on a specified position. While another index mark signal is delivered in the form of a signal including the data on the time when the rotary storage medium of the 2nd device 27 passes a specific position. This latter index mark signal is applied to a comparator 13 as a target signal 14 to be compared with the first index mark signal. Thus the synchronization is possible for the revolving positions between the 1st and 2nd disk devices.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a rotary external storage device 4 such as a magnetic disk device,
More specifically, the present invention relates to a rotating external storage device consisting of a plurality of storage devices H.

In order to improve the reliability of a computer system, it has been considered to record the same content on multiple disk drives (:jj) to recover from a system failure caused by a single failure.

For this purpose, multiple recording media (0
1) A: It is possible to consider a device with a head disk assembly (head disk assembly), but in that case, since the rotating system is common, they will fail together in the event of a failure, reducing reliability, so it is recommended to use independent devices. It is desirable to implement them side by side.

In the case of independent devices, each device rotates at almost the same speed, but the rotational position (phase) at a given moment is different, so
When a program instructs one disk device to write the same content, it takes nearly twice as long to complete the entire process as in the case of one disk device, resulting in a significant reduction in system throughput.

The peripheral control device has a buffer memory and writes to the buffer memory at the same time it is written to the peripheral control device. A method has also been proposed in which the device independently executes a write operation to the copy disk capacity.

However, this is before all of the actual 1iK have been completed (
There are problems with reliability, such as the amount of buffer memory caused by accepting the next input/output operation during the previous replication operation, an increase in the number of data transfer paths, and problems with the complexity of ``rli'' control. However, the disadvantage is that it becomes a fairly large device.

An object of the present invention is 1) to provide a rotating external storage device with a simple configuration that can prevent the decrease in system throughput mentioned above.

In order to achieve the above object, the present invention provides a rotary external memory.
[Each λ machine has an electrical rotation speed of 1 flll.
In a rotary external storage device consisting of a first and a second rotary storage device that can be flilled, the time at which the rotary storage medium of the device passes a certain point 14 from the first rotary storage device is determined by the first rotary storage device. Extract the signal containing the data, and combine this signal with the rotation record of the second rotary distribution pipe;
The rotation of the second rotary storage device is controlled based on the comparative output of a signal containing data on the time when the zero medium passes a certain specific position, and the second rotational storage device is The structure is such that it is rotated over the same circumference as the rotation form 1i' and with a constant phase relationship t'!.

According to the above configuration, a decrease in system throughput can be prevented and the object of the present invention can be completely achieved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below by taking a magnetic disk device as an example with reference to some drawings.

When recording information on a magnetic disk, it is necessary to know the absolute rotational position of the disk, and conventionally index marks based on optical or magnetic patterns have been used for this purpose. In the present invention, the above-mentioned conventional technology can be used as is for generating a signal containing data on the time when the rotating storage medium of the first disk device passes a certain specific position, that is, a pulse signal indicating the rotational position.

The pulse signal is notified to the second disk device. In this case, it is possible to use either an electrical signal or an optical signal. This is easily done using known techniques.

The method of rotation synchronization in disk drives 1 and 2 will be explained by taking as an example a rotation system using a servo motor, which has begun to be adopted in small and medium-sized disk drives.

The servo motor at -4' is configured as shown in FIG. In FIG. 1, reference numeral 11 denotes a driving portion such as a motor, which exerts a driving force according to the output from an amplifier 12. A detector 15 attached to the drive unit 11 converts a controlled variable, for example, rotational speed, into an electrical signal, and a comparator 13 generates a difference from the target value given at 14 and transmits it to the amplifier 12. As a result, even if the drive unit 1 itself does not have a constant speed rotation ability, constant speed rotation matching the target value determined in step 14 can be performed. Recognizing the rotational position rather than the rotational speed is taken as the control variable, a pulse indicating the target rotational position is given from ]4, and the difference between both rotational positions (difference in time of passing a specific position) is converted into an electrical signal by the comparator 13. If the signal is changed into a signal and applied to the amplifier 12, not only constant speed rotation but also rotation that maintains a constant phase can be achieved.

This is called a d-phase locked loop (PLL), and many magnetic disk drives that use servo motors also use this method. The position information from 5 is given as n (n) 1) pulses per rotation, and the target signal 14 is simply connected to an oscillator output that outputs pulses at a constant cycle, so rotational position recognition in the true sense is possible. In the present invention, if the rotation system of the second disk device is shown in FIG. On the other hand, an index mark signal is given as a target signal 14, similar to the first disk drive, and by comparing and amplifying these signals, the rotational position 11 of the first and second disk drives is determined. can be synchronized.

Note that it is desirable for the second disk device to switch the reference pulse 14 to the reference pulse generator within the second disk device when the index mark pulse period from the first disk device exceeds a certain tolerance range. , this will not be discussed in detail. Taiko's technology is easily realized by those in the industry.

FIG. 2 shows an example in which a disk device having the above functions is used in a computer system.

In FIG. 2, a 21-digit main memory device fi;t, 22
．． is a central processing unit, 23 is a channel control device, 24
, 25 is a peripheral (disk) control device, 26 and 27 are magnetic disk devices, and 28 is a magnetic disk device +N26.27
This is the index mark pulse line used to synchronize the rotation of the motor. The software program recognizes in advance that rotational synchronization is established between the magnetic disk drives 26 and 27, and allocates the recording area of important information to this disk drive in duplicate.

During actual writing, output requests for the same content are given to these two devices using different channels. Processing is completed in almost the same time as with one machine.

The sameness of the double disk drive may be temporarily disturbed by some external factor, and it may not be possible to record at the same position between the duplicate disk drives to avoid partial defects in the recording medium. However, in any case, there is no logical problem, only a temporary) or partial decrease in processing efficiency.

Figure 2 shows an example in which one disk device is connected to each peripheral device, but unlike this, it is also possible to synchronize the rotation between two disk devices under one peripheral control device. It is possible. In this case, it is necessary to adopt an architecture in which one output Yasugi writes to two drives at the same time, and the peripheral control device has a buffer memory that absorbs the slight 1υ1 discrepancy between the two drives, and data can be written to two disk drives at the same time. Although the ability to transfer data is required, this method causes less deterioration in system performance.

As is clear from the above description, according to the present invention, multiple writing can be performed on a plurality of rotating storage devices without substantially reducing system performance, and system reliability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the concept of a servo motor, and FIG. 2 is a diagram showing an example of how the device of the present invention is used in a computer system. 11...1 drive unit (motor) 12...'' (3 width controller 1
3... Ratio diO unit 14... Reference signal (target value)
]5...Detector 21...Main storage device 22...
Central processing unit 23...channel control device 24,
25... Peripheral (disk) '1t71J Gosha holder 26.
27...Magnetic disk device according to the present invention 28...Synchronization signal line (index mark pulse line) of the present invention Patent applicant NEC Corporation Representative Patent attorney Hisashi Inoro:,l・1)η 2・Figure 2

Claims (1)

[Claims] In the rotary external storage ft1i device 4, which is composed of a first and a second rotary storage medium whose rotational speed can be controlled mechanically, there is a rotary storage medium of this storage device from the first rotary storage device. A signal containing data on the time when the rotation recording medium of the second rotation storage medium passes through a certain specific position is extracted from a comparison output of this signal and a signal containing data on the time when the rotation record medium of the second rotation storage medium passes through a certain specific position. It is characterized in that the rotation of the rotary memory device N is controlled so that the second rotary memory device is rotated at the same period as the first rotary memory device and with a substantially constant phase relationship. Rotating external storage device.