Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
1998-03-25
2001-04-24
Kim, Matthew (Department: 2186)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
Reexamination Certificate
active
06223251
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a disk processing apparatus and a recording medium for controlling a disk storage device to be used as data storage means for a computer.
BACKGROUND OF THE INVENTION
Typical data storage means for a computer is a magnetic disk drive, and an architecture for improving availability of such a magnetic disk drive is known as RAID (Redundant Array of Inexpensive (or Independent) Disks).
RAID-
1
is equated with “mirroring” and is alternatively called “duplexing” in a case where separate disk controllers (SCSI: Small Computer system Interface; IDE: Intelligent Drive Electronics) are used. Its operations, with respect to physically separate two disks having the same capacity, are carried out as follows:
read: reading from either one of the disks; and
write: writing into both disks.
RAID-
5
,
6
is a technique which is adapted for striping data and distributing such data called “striped data set” across a plurality of hard disks, thereby to improve availability in the presence of disk failure, if any. Its operations, with respect to physically separate n disks having the same capacity, are carried out as follows:
write: writing data into (n-
1
) disks,
and
writing parity into a single disk (RAID-
5
)
or
writing parity into two disks (RAID-
6
); and
read: reading data other than parity. Or, in case of a disk failure, reading data and parity together.
Problems to be Solved by the Invention
However, in said RAID-
1
,
5
and
6
, there are problems as set forth below.
A length of data writing areas of the outermost track on a hard disk is about two times as large as that of the innermost track, and in order to make the recording density constant, a technique called “Zone Bit Recording (ZBR)” has been used for reducing the number of recording sectors with movement toward the inner tracks. Therefore, the read/write access rate at the outer tracks is faster than that of the inner tracks. However, in the conventional RAID-
1
, every read/write to two disks has been carried out without taking into account any difference of access rate among their zones at all. That is, as detailed hereafter, the characteristic of the ZBR has not been contemplated for improving access rate of each disk.
Similarly, with respect to RAID-
5
,
6
, there are the same problems as set forth above.
It is, therefore, an object of this invention to provide a disk processing apparatus and a recording medium which are capable of solving the aforesaid problems and improving access rate.
SUMMARY OF THE INVENTION
To accomplish said object, in one aspect of the invention, there is provided a disk processing apparatus having at least two disks, each having outer tracks and inner tracks that include fewer sectors than said outer tracks. This disk processing apparatus comprises a write controller for writing identical data into a first disk and a second disk of said at least two disks such that said identical data is written into at least a portion of the outer tracks of said first disk and into at least a portion of the inner tracks of said second disk respectively, said second disk being different from said first disk.
In another aspect of the invention, there is provided a recording medium for recording a control program executable by a computer to write data into at least two disks of a disk processing apparatus such that said computer is caused to write identical data into at least a portion of outer tracks of a first disk and at least a portion of inner tracks of a second disk of said at least two disks respectively.
Preferably, said recording medium is be a ROM.
Further, said recording medium may be provided in an I/O processor for a disk device connected to a system bus of a computer system.
Further, in another aspect of the invention, there is provided a disk processing apparatus having at least three disks, each having outer tracks and inner tracks that include fewer sectors than said outer tracks. This disk processing apparatus comprises a data write controller for writing a striped data set across at least respective portions of outer tracks of a first disk and a second disk of said at least three disks, and a parity write controller for writing the parity that is associated with said data set written into said first and second disks into at least a portion of the inner tracks of a third disk of said at least three disks, said third disk being different from said first and second disks.
Further, in another aspect of the invention, there is provided a recording medium for recording a control program executable by a computer to write data into at least three disks of a disk processing apparatus such that said computer is caused to write a striped data set across at least respective portions of outer tracks of a first disk and a second disk of said at least three disks, and to write the parity associated with said data set written into said first and second disks into at least a portion of the inner tracks of a third disk of said at least three disks, said third disk being different from said first and second disks.
Preferably, said recording medium is a ROM.
Further, said recording medium may be provided in an I/O processor for a disk device connected to a system bus of a computer system.
REFERENCES:
patent: 5893138 (1999-04-01), Judd et al.
patent: 5900101 (1999-05-01), Aoki et al.
patent: 5915094 (1999-06-01), Kouloheris et al.
patent: 5974544 (1999-10-01), Jeffries et al.
“The performance of Parity Placements in Disk Arrays,” Lee and Katz, IEEE Transactions on computers, vol. 42, No. 6, Jun. 1993, pp. 651-664.*
“Methods for Improved Update Performance of Disk Arrays,” Menon and Kasson, IBM Research Division, Almaden Research Center, San Jose, CA, Res., Rep., RJ 6928 (66034), 1989.
Chace C. P.
International Business Machines - Corporation
Kim Matthew
Klein Esther E.
Raissinia Abdy
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