Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
1998-04-21
2001-03-27
Bragdon, Reginald G. (Department: 2185)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C714S006130
Reexamination Certificate
active
06209060
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a disk array device for accessing a plurality of disk devices in parallel and executing input and output of data.
BACKGROUND OF THE INVENTION
Currently, a magnetic disk device, which is regarded as one satisfying requirements such as large capacity and rapid data transfer, is widely used as an external storage device for a computer system.
In recent years, a disk array device has received attention as a device which further satisfies high reliability and low price in addition to the above requirements. The disk array device is obtained by arranging a plurality of compact disk devices into which data is distributed for storage therein respectively.
David A. Patterson et al. of the University of California at Berkeley released a paper in which a large amount of data was distributed to many physical disks, and a disk array device for realizing redundancy of data in the event of disk failure was evaluated with classification thereof from Level 1 to Level 5 (ACM SIGMOD Conference, Chicago, Jun. 1-3, 1988, P109 to P116). The levels 1 to 5 for classifying a disk array device proposed by David A. Patterson et al. are referred to as RAID (Redundant Arrays of Inexpensive Disks) 1 to 5.
All the disk array devices have redundant data therein. Accordingly, even if a disk device constituting an array can not be used because of some problem and data can not be read out therefrom, it is possible to recover disappeared data by using the redundant data and remaining data.
However, if any of the disk devices remains faulty, the redundancy of the disk array device is low although recovery of the data is possible with difficulty. For this reason, when a disk device constituting the array is faulty, the disk device is removed from the arrayed disk devices as quickly as possible and a normal disk device needs to be incorporated therein anew.
Accordingly, when a disk device is faulty, the faulty disk is replaced with another disk for maintenance. But a version number of the firmware recorded in the disk device used for maintenance may be different from that of the disk devices which are already operating in the disk array device.
As the arrayed disk devices are operated by logically correlating a plurality of disk devices to each other as described above, it is desirable that all operations be the same on the correlated disks. That is because usage of disk devices with different version numbers of the firmware may cause contradiction in control logic, which may in turn generate an operational error.
SUMMARY OF THE INVENTION
It is an object of the present invention to realize a disk array device which insures stable operations even when a disk device constituting an array is replaced.
Each disk device constituting a disk array device has firmware for operating itself on each of the disk media. Each of the disk devices reads in firmware on a memory when power is turned ON and is controlled according to the firmware after completion of the operation for reading the firmware in.
Accordingly, to solve the problems as well as to achieve the object as described above, a disk array device according to the present invention comprises a logical disk consisting of an I/O device for storing data therein and an I/O device for storing therein redundant data pared with the data, a lower device interface control section connected to a plurality of I/O devices constituting the logical disk for transferring data to and from the I/O devices, an upper device interface control section connected to an upper device as well as to the lower device interface control section for analyzing an operational instruction to the logical disk issued from the upper device and also for transferring data to and from the lower device interface control section, and a control unit for controlling the lower device interface control section and the upper device interface control section. Each of the I/O devices has a rewritable nonvolatile storage medium with a control program controlling the device itself and a version number of the control program stored therein.
The disk array device is also characterized in that the control unit has a detecting unit for detecting that any of the plurality of I/O devices has been replaced, and a copying unit for transferring and storing in an I/O device detected by the detecting unit a control program for I/O devices other than the one among the plurality of I/O devices.
With the disk array device according to the present invention, a control program of a replaced disk is matched with a control program of an existing disk, so that the reliability of a disk array device can be improved.
A disk array device according to the present invention comprises a logical disk consisting of an I/O device for storing data therein and an I/O device for storing therein redundant data prepared with the data, a lower device interface control section connected to a plurality of i/O devices constituting the logical disk for transferring data to and from the I/O devices, an upper device interface control section connected to an upper device as well as to the lower device interface control section for analyzing an operational instruction to the logical disk issued from the upper device and also for transferring data to and from the lower device interface control section, and a control unit for controlling the lower device interface control section and the upper device interface control section. Each of the I/O devices has a rewritable nonvolatile storage medium with a control program controlling the device itself and a version number of the control program stored therein. The disk array device is also characterized in that the control unit has a detecting unit for detecting that any of the plurality of I/O devices has been replaced, a reference device selecting unit for selecting, when it is detected by the detecting unit that any of the I/O devices has been replaced, an I/O device other than the replaced one from the plurality of I/O devices, and a copying unit for transferring and storing a control program stored in the I/O device selected by the reference device selecting unit in the replaced I/O device.
With the disk array device according to the present invention, when a disk is replaced during system operation, a reference disk is selected from the disk devices other than the disk device having been replaced in the step of disk replacement, and firmware of the reference disk is copied into the disk device having been replaced in the disk replacement step, so that, in addition to improvement of the reliability of the disk array device, firmware can be updated to the replaced disk even during system operation. As a result, a time for maintenance is not required, and for this reason convenience of the devices can be improved.
In a disk array device according to the present invention, the reference disk selecting unit previously allocates at least two disk devices among the plurality of disk devices as reference disks and selects, when either one of the two disk devices is a disk device having been replaced in the step of disk replacement described above, another disk device as a reference disk device.
With the disk array device according to the present invention, when either one the two disk devices having previously been allocated as reference disks is a disk device having been replaced in the step of disk replacement described above, another disk device is selected as a reference disk device, so that a logical disk can be maintained at any time in fixed firmware when the disk is replaced.
A disk array device according to the present invention comprises a logical disk consisting of an I/O device for storing data therein and an I/O device for storing therein redundant data prepared with the data, a lower device interface control section connected to a plurality of I/O devices constituting the logical disk for transferring data to and from the I/O devices, an upper device interface control section connected to an upper device as well as to the lower device interface con
Bragdon Reginald G.
Fujitsu Limited
Staas & Halsey , LLP
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