High capacity disk storage system having unusually high fault tolerance level and bandpass

• US 4,722,085 A
• Filed: 02/03/1986
• Issued: 01/26/1988
• Est. Priority Date: 02/03/1986
• Status: Expired due to Term

• Current Assignee: Unisys Corporation
• Original Assignee: Unisys Corporation
• Inventors: Ruby, Gary V., Flora, Laurence P.
• Primary Examiner(s): Fleming, Michael R.
• Application Number:
  US06/825,174
• Time in Patent Office: 722 Days
• Field of Search: 371/37, 371/38, 371/39, 371/40, 371/10, 371/21, 364/200, 364/900
• US Class Current: 714/770
• CPC Class Codes: G06F 11/00 Error detection; Error correction; Monitoring error detection, correction or monitoring in information storage based on relative movement between record carrier and transducer G11B20/18; monitoring, i.e. supervising the progress of recording or reproducing G11B27/36; in static stores G11C29/00
• CPC Class Codes: G06F 11/10 Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G11B 20/1833 by adding special lists or symbols to the coded information G11B20/1806, G11B20/1866 take precedence

Abstract

A relatively large plurality of relatively small, independently operating disk subsystems are coupled to a read/write interface containing error circuitry and data organizer circuitry. The data organizer circuitry organizes read/write data for read/write communication with the disk subsystems via the error circuitry such that the overall system appears as a large, high capacity disk system having an unusually high fault tolerance and a very high bandpass.

Claims

1. A high capacity disk storage system comprising:

a relatively large plurality of independently operable disk subsystems, each disk subsystem comprising disk means containing stored data, wherein data is stored on the disk means of said disk subsystems in the form of data words, each data word comprising a plurality of data digits along with a plurality of associated error check digits, each disk means storing one digit from each data word;

means coupled to said disk subsystems for reading a data word from the disk means thereof and for producing data word electrical signals corresponding thereto; and

error circuit means to which said data word electrical signals are applied, said error circuit means being operable to produce electrical signals corresponding to the data digits of a data word read from said disk means, in a manner such that an error in a data digit will be detected and corrected by said error circuit means using the associated error check digits of the data word.

2. The invention in accordance with claim 1, wherein said system includes coupling means for applying to said error circuit means electrical signals corresponding to data digits of a data word to be written on said disk means, wherein said error means is operable in response to these applied electrical signals corresponding to the data digits of a data word to be written to produce electrical signals corresponding to a data word comprised of these data digits and associated error check digits derived therefrom, and wherein said system includes means coupled to said disk subsystems for writing a data word corresponding to these data word electrical signals produced by said error circuit means on said disk means in a manner such that each disk means stores one digit of the written data word.

3. The invention in accordance with claim 2, wherein each digit comprises a binary bit.

4. The invention in accordance with claim 2, including storage control means, and wherein said coupling means is operative to receive data from said storage control means which is to be written on said disk means for organizing this received data into electrical signals corresponding to data digits of a data word for application to said error circuit means.

5. The invention in accordance with claim 4, wherein said coupling means is also operative to receive electrical signals produced by said error circuit means corresponding to data digits of a data word read from said disk means and to transmit electrical signals corresponding thereto to said storage control means.

6. The invention in accordance with claim 2, wherein the digits of a data word are read from said disk means in parallel.

7. The invention in accordance with claim 6, wherein the digits of a data word are written in parallel on said disk means.

8. The invention in accordance with claim 7, wherein the parallel reading and writing of a data word is provided at a common location for all of said disk means.

9. A high capacity disk storage system comprising:

a relatively large plurality of separately operable disk means for storing data;

writing means for writing data on said disk means in the

form of data words, each data word being comprised of a plurality of data digits and an associated plurality of error check digits chosen so as to permit an error in at least one digit of a data word to be detected and corrected, each disk means storing a respective one of said digits;

reading means for reading data words from said disk means; and

error circuit means to which data words read from said disk means are applied, said error circuit means producing output electrical signals corresponding to the data digits of each applied data such that an error in a data digit of an applied data word is corrected.

10. The invention in accordance with claim 9, wherein said reading means and said writing means operate in parallel with respect to said disk means.

11. The invention in accordance with claim 10, including means for applying an address to said reading and writing means which determines the address at which reading or writing is performed on said disk means, said address being common to all of said disk means.

12. A high capacity disk storage system comprising:

a relatively large plurality of separably operable disk subsystems;

each disk subsystem including disk means for storing data, wherein data is stored on the disk means of said subsystems in the form of data words, each data word being comprised of a plurality of data digits and an associated plurality of error check digits chosen so as to permit an error in at least one digit of a data word to be detected and corrected, each disk means storing a respective one of the digits of a data word;

each disk subsystem also including controller means for reading a selectable predetermined plurality of digits from its respective disk means;

each disk subsystem additionally including buffer means for storing digits read from its respective disk means by its respective controller means;

error circuit means operable to receive a data word and to provide error detection and correction therefor using the data error check digits thereof such that electrical signals are outputted by said error circuit means corresponding to the data digits of an applied data word, wherein an error occurring in one of the data digits is corrected; and

coupling means coupled to the controller means of said disk subsystems for transferring data digits stored in the buffer means of said subsystems to said error circuit means in the form of data words.

13. A high capacity disk storage system comprising:

a relatively large plurality of separably operable disk subsystems;

each disk subsystem including disk means for storing data, controller means capable of reading data from and writing data on its respective disk means at a selectable address, and buffer means for storing data read from its respective disk means by its respective controller means and for storing data to be written on its respective disk means by its respective controller;

means for storing data words to be written on said disk means in the buffer means of said subsystems, each data word being comprised of data digits and associated error check digits chosen so as to permit the data digits of a data word to be determinable even if there is an error in a digit of the data word, each data word being stored in said buffer means such that each buffer means stores a respective one of the digits thereof;

each controller means being operable in parallel with the other controller means and in response to an applied address to write digits stored in its respective buffer means on its respective disk means at a location determined by said address;

each controller means also being operable in parallel with the other controller means in response to an applied address commonly applied to all of said controller means to read digits from its respective disk means at a location determined by said address and to store the digits read in its respective buffer means;

each controller means further being operable in parallel with the other control means and in response to a transmission signal commonly applied to all of said control means to cause a digit of a data word to be outputted from each buffer so as to thereby form a data word; and

error circuit means responsive to a data word outputted from said buffer means for providing electrical output signals corresponding to the data digits thereof, wherein an error in a data digit will have been corrected by said error circuit means using the associated error check digits of the data word.

14. The invention in accordance with claim 13, wherein said controller means is operable in response to said initiation signal to cause said buffer means to successively output a predetermined plurality of data words to said error circuit means.

15. The invention in accordance with claim 14, wherein said initiation signal is provided at a time chosen such that all of the respective digits of each data word to be outputted will have been read into their respective buffer means by their respective controller means.

16. The invention in accordance with claim 13, wherein a common address is applied to all of said controller means for reading and writing.

17. The invention in accordance with claim 13, wherein each disk means includes at least one rotatable disk and cooperating head means;

and wherein sufficient time is allowed for the aforesaid reading and writing provided by said controller means to accommodate worst case positioning of the head means relative to the addressed location of their respective disks.