Data storage system with asynchronous host operating system communication link

• US 5,257,367 A
• Filed: 07/17/1990
• Issued: 10/26/1993
• Est. Priority Date: 06/02/1987
• Status: Expired due to Term

• Current Assignee: Storage Computer Corporation
• Original Assignee: Cab-Tek, Inc.
• Inventors: Sarkozy, Andras, Kacirek, Raul, Selmeczi, Janos, Goodlander, Theodore J., Hetenyi, Tamas
• Primary Examiner(s): Shaw, Gareth D.
• Assistant Examiner(s): Chavis, John Q.
• Application Number:
  US07/554,127
• Time in Patent Office: 1,197 Days
• Field of Search: 395/600, 395/600 MS File
• US Class Current: 1/1
• 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: G06F 11/22 Detection or location of defective computer hardware by testing during standby operation or during idle time, e.g. start-up testing
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 13/36 for access to common bus or bus system
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0673 Single storage device
• CPC Class Codes: G11B 20/1833 by adding special lists or symbols to the coded information G11B20/1806, G11B20/1866 take precedence
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

This invention provides disk drive access control apparatus for connection between a host computer and a plurality of disk drives to provide an asynchronously operating storage system. It also provides increases in performance over earlier versions thereof. There are a plurality of disk drive controller channels connected to respective ones of the disk drives and controlling transfers of data to and from the disk drives, each of the disk drive controller channels includes a cache/buffer memory and a micro-processor unit. An interface and driver unit interfaces with the host computer and there is a central cache memory. Cache memory control logic controls transfers of data from the cache/buffer memory of the plurality of disk drive controller channels to the cache memory and from the cache memory to the cache/buffer memory of the plurality of disk drive controller channels and from the cache memory to the host computer through the interface and driver unit. A central processing unit manages the use of the cache memory by requesting data transfers only of data not presently in the cache memory and by sending high level commands to the disk drive controller channels. A first (data) bus interconnects the plurality of disk drive cache/buffer memories, the interface and driver unit, and the cache memory for the transfer of information therebetween and a second (information and commands) bus interconnects the same elements with the central processing unit for the transfer of control and information therebetween.

Claims

1. In a computer system including a host computer (10) connected to access a plurality of data storage units (16,36) and including an operating system (12) having tables of file locations (25) of data stored on said data storage units, the improvement comprising:

a) data storage unit access control means (28) connected between the host computer (10) and the plurality of data storage units (16,36), for receiving read and write requests from the host computer, said read and write requests including data file manipulation commands and associated data file storage locations, for reading and writing data from and to the plurality of data storage units, and for transferring data to and from the host computer;

b) host computer link means (18,24,20), connected between said data storage access control means (28) and said host computer (10), for establishing a first read and write request data path between said host computer and said data storage access control means, for providing said data storage access control means (28) with said read and write requests from said host computer (10), and for transferring data to and from said host computer (10);

c) host computer operating system communications link means (34,32), connected between said data storage unit access control means (28) and a console privilege interface (26) to the host computer operating system (12), for establishing a second read and write request data path between said host computer and said data storage access control means, for obtaining and providing said data storage unit access control means (28) with data file manipulation commands from said operating system (12) and associated data file storage locations from said operating system tables of file locations (25) of data stored on said data storage units (16,36), said data file manipulation commands for directing said data storage units to manipulate predetermined data stored in said data file storage locations associated with said data file manipulation commands; and

,

d) computational logic means (40) contained in said data storage unit access control means (28) and responsive to at least said data file manipulation commands and associated data file storage locations received over said host computer operating system communications link means (34,32), for providing data storage unit command signals directing said data storage units to manipulate said predetermined data stored in said data file storage locations associated with said data file manipulation commands asynchronously with and independent of said read and write requests from said host computer over said first read and write request data path established by said host computer link means (18,24,20), whereby the host operating system provides transparency about data file manipulation commands to user programs operating within the host computer and reading and writing data to and from the plurality of data storage units over said host computer link means (34,32).

2. The improvement to a computer system of claim 1 wherein:

said computational logic means includes learning logic so that once the location of a requested data on the plurality of data storage units has been obtained using said communications link means, it is known and remembered.

3. The improvement to a computer system of claim 1 wherein:

a) the computer system includes near line archival storage apparatus of an automated variety wherein off-line storage media are loaded for reading and writing on request by automated mechanisms; and

,

b) said computational logic means includes logic for using said communications link means to obtain file location information about data on said near line storage apparatus.

4. The improvement to a computer system of claim 3 wherein additionally:

said computational logic means includes learning logic so that once the location of a requested data on said near line storage apparatus has been obtained using said communications link means, it is known and remembered.

5. The improvement to a computer system of claim 4 wherein additionally:

said learning logic of said computational logic means is of a self learning variety which learns through experience so that if a particular file from said near line storage apparatus is repeatedly used at a given time said learning logic learns that from experience and begin loading said file from said near line archival storage apparatus in anticipation of an expected request so that when said request is made, said file is already read in and available for use.

6. The improvement to a computer system of claim 1 wherein:

said computational logic means includes testing logic for testing the plurality of data storage units in a background mode on a time-available basis.

7. The improvement to a computer system of claim wherein said data storage unit access control means comprises:

a) a plurality of data storage unit controller channel means connected to respective ones of the plurality of data storage units for controlling transfers of data to and from an associated one of the plurality of data storage units in response to received high level commands, each of said plurality of data storage unit controller channel means including a cache/buffer memory and a micro-processor unit for controlling said transfers of data and status;

b) interface and driver unit means for interfacing with said communications link means and the host computer;

c) a central cache memory;

d) cache memory control means for controlling transfers of data from said cache/buffer memory of said plurality of data storage unit controller channel means to said cache memory and from said cache memory to said cache/buffer memory of said plurality of data storage unit controller channel means and from said cache memory to the host computer through said interface and driver unit means;

e) central processing unit means for managing the use of said cache memory by requesting data transfers only with respect to ones of the plurality of data storage units where data associated therewith is not presently in said cache memory and for sending high level commands to said plurality of data storage unit controller channel means to effect data transfers thereby;

f) first (data) bus means interconnecting said plurality of data storage unit controller cache/buffer memories, said interface and driver unit cache/buffer memory and said cache memory for the transfer of information therebetween; and

,

g) second (information and commands) bus means interconnecting said plurality of data storage unit controller channel means, said interface and driver unit means, said cache memory control means, and said central processing unit means for the transfer of control information therebetween.

8. The improvement to a computer system of claim 7 wherein said data storage unit access control means includes:

a) an alphanumeric display; and

,

b) driver means for driving said display.

9. The improvement to a computer system of claim 7 wherein said interface and driver unit means comprises:

a) first bus driver means for connecting to and interfacing with said first bus;

b) host computer interface driver means for connecting to and interfacing with the host computer;

c) communications link interface means for connecting to and interfacing with said communications link means;

d) a first unidirectional FIFO connected between said first bus driver means and said host computer interface driver means for receiving inputs from said first bus intended for the host computer;

e) a second unidirectional FIFO connected between said host computer interface driver means and said first bus driver means for receiving inputs from the host computer intended for said first bus;

f) local micro-processor means for controlling said first unidirectional FIFO, said second unidirectional FIFO, and said host computer interface driver means; and

,

g) connector means for connecting said local micro-processor means to said second bus.

10. The improvement to a computer system of claim 7 wherein each of said plurality of data storage unit controller channel means comprises:

a) first bus driver means for connecting to and interfacing with said first bus;

b) data storage unit interface driver means for connecting to and interfacing with an associated one of the plurality of data storage units;

c) a data buffer;

d) data semaphore means for preventing simultaneous access to said data buffer by said first bus driver means and said data storage unit interface driver means;

e) buffer address register means for providing a current active address into said data buffer;

f) local micro-processor means for controlling said data semaphore means and said data storage unit interface driver means; and

,

g) connector means for connecting said local micro-processor means to said second bus.

11. In a computer system including a host computer connected to access a plurality of disk drives to provide an asynchronously operating, improved disk drive access control apparatus connected between the host computer and the plurality of disk drives for receiving read and write requests from the host computer, for reading and writing data from and to the plurality of disk drives, and for transferring data to and from the host computer, said disk drive access control apparatus (28) comprising:

a) a plurality of disk drive controller channel means (48) connected to respective ones of the plurality of disk drives (16), for controlling transfers of data to and from an associated one of the plurality of disk drives in response to received high level commands, each of said plurality of disk drive controller channel means including a cache/buffer memory (48) and a micro-processor unit (50) for controlling said transfers of data;

b) interface and driver unit means (42), for interfacing with a host computer operating system communications link means (32,34) connected between said disk drive access control apparatus and a console privilege interface to a host computer operating system, said host computer operating system communications link means for establishing a second read and write request data path between said host computer and said interface and driver unit means, and for interfacing with a host computer link means connected between said disk drive access control apparatus and the host computer, said host computer link means for establishing a first read and write request data path between said host computer and said data storage access control means;

c) a central cache memory (56);

d) cache memory control means (54), for controlling transfers of data from said cache/buffer memory of said plurality of disk drive controller channel means to said cache memory and from said cache memory to said cache/buffer memory of said plurality of disk drive controller channel means and from said cache memory to the host computer through said interface and driver unit means;

e) central processing unit means (60) for managing the use of said cache memory (54) by requesting data transfers only with respect to ones of the plurality of disk drives where data associated therewith is not presently in said cache memory, for sending high level commands to said plurality of disk drive controller channel means to effect data transfers thereby, and for receiving over said host computer operating system communication link means (32,34), data file manipulation commands from said host computer operating system and associated data file storage locations from data storage unit file location tables maintained by said host computer operating system over said second read and write request data path, for providing data storage unit command signals controlling manipulation of predetermined data stored in said data file storage locations associated with said data file manipulation commands asynchronously with and independently of read and write requests received from said host computer over said first read and write request data path established by said host computer link means;

f) first (data) bus means interconnecting said plurality of data storage unit controller cache/buffer memories, said interface and driver unit means, said cache/buffer memory and said cache memory, for the transfer of information therebetween; and

,

g) second (information and commands) bus means interconnecting said plurality of data storage unit controller channel means, said interface and driver unit means, said cache memory control means, and said central processing unit means for the transfer of control information therebetween.

12. The improvement to a computer system of claim 11 wherein said disk drive access control means includes:

a) an alphanumeric display; and

,

b) driver means for driving said display.

13. The improvement to a computer system of claim 11 wherein said interface and driver unit means comprises:

a) first bus driver means for connecting to and interfacing with said first bus;

b) host computer link interface driver means, for connecting to and interfacing with the host computer;

c) host computer operating system communications link interface driver means, for connecting and interfacing with said host computer console privilege interface;

d) a first unidirectional FIFO connected between said first bus driver means and said host computer interface driver means, for receiving inputs from said first bus intended for the host computer;

e) a second unidirectional FIFO connected between said host computer interface driver means and said first bus driver means for receiving inputs from the host computer intended for said first bus;

f) local micro-processor means for controlling said first unidirectional FIFO, said second unidirectional FIFO, and said host computer interface driver means; and

,

g) connector means for connecting said local micro-processor means to said second bus.

14. The improvement to a computer system of claim 11 wherein each of said plurality of disk drive controller channel means comprises:

a) first bus driver means for connecting to and interfacing with said first bus;

b) disk drive interface driver means for connecting to and interfacing with an associated one of the plurality of disk drives;

c) a data buffer;

d) data semaphore means for preventing simultaneous access to said data buffer by said first bus driver means and said disk drive interface driver means;

e) buffer address register means for providing a current active address into said data buffer;

f) local micro-processor means for controlling said data semaphore means and said disk drive interface driver means; and

,

g) connector means for connecting said local micro-processor means to said second bus.

15. Disk driver access control apparatus for connection between a host computer (10) and a plurality of disk drives (16) to provide an asynchronously operating, storage system to receive read and write requests from the host computer, said read and write requests including data file manipulation commands and data file storage locations, for reading and writing data from and to the plurality of disk drives, and for transferring data to and from the host computer, said apparatus comprising:

a) a plurality of disk drive controller channels (48) connected to respective ones of the plurality of disk drives (16) and controlling transfers of data to and from an associated one of the plurality of disk drives in response to received high level commands, each of said plurality of disk drive controller channels including a cache/buffer memory (48) and a micro-processor unit (50) for controlling said transfers of data;

b) an interface and driver unit (42) interfacing with a host computer operating system communications link (32,34) connected between said disk drive control apparatus and a console privilege interface to a host computer operating system, and a host computer link connected between said disk drive access control apparatus and said host computer, said host computer link for establishing a first read and write request data path between said host computer and said data storage access control apparatus, said host computer operating system communications link for establishing a second read and write request data path between said host computer and said interface and driver unit;

c) a central cache memory (56);

d) cache memory control logic (54) controlling transfers of data from said cache/buffer memory of said plurality of disk drive controller channels to said cache memory and from said cache memory to said cache/buffer memory of said plurality of disk drive controller channels and from said cache memory to the host computer through said interface and driver unit;

e) a central processing unit (60) managing the use of said cache memory by requesting data transfers only with respect to ones of the plurality of disk drives where data associated therewith is not presently in said cache memory and by sending high level commands to said plurality of disk drive controller channels to effect data transfers thereby, and for receiving over said host computer operating system communication link (32,34), data file manipulation commands from said host computer operating system and associated data file storage locations from data storage unit file location tables maintained by said host computer operating system over said second read and write request data path, for providing data storage unit command signals controlling manipulation of predetermined data stored in said data file storage locations associated with said data file manipulation commands asynchronously with and independent of read and write requests from said host computer over said first read and write request data path established by said host computer link;

f) a first (data) bus interconnecting said plurality of data storage unit controller cache/buffer memories, said interface and driver unit cache/buffer memory and said cache memory for the transfer of information therebetween; and

,

g) second (information and commands) bus interconnecting said plurality of data storage unit controller channel means, said interface and driver unit, said cache memory control logic, and said central processing unit for the transfer of control information therebetween.

16. The disk drive access control apparatus of claim 15 wherein said disk drive access control logic includes:

a) an alphanumeric display; and

,

b) driver means for driving said display.

17. The disk drive access control apparatus of claim 15 wherein said interface and driver unit comprises:

a) first bus driver means for connecting to and interfacing with said first bus;

b) host computer link interface driver means for connecting to and interfacing with the host computer;

c) host computer operating system communication link interface driver means, for connecting to and interfacing with said host computer operating system console privilege interface;

d) a first unidirectional FIFO connected between said first bus driver means and said host computer interface driver means for receiving inputs from said first bus intended for the host computer;

e) a second unidirectional FIFO connected between said host computer interface driver means and said first bus driver means for receiving inputs from the host computer intended for said first bus;

f) local micro-processor means for controlling said first unidirectional FIFO, said second unidirectional FIFO, and said host computer interface driver means; and

,

g) connector means for connecting said local micro-processor means to said second bus.

18. A method of operating the disk drive access control apparatus of claim 17, wherein said apparatus performs the steps of:

a) controlling transfers of data from the cache/buffer memory of the plurality of disk drive controller channels to the cache memory and from the cache memory to the cache/buffer memory of the plurality of disk drive controller channels and from the cache memory to the host computer through the interface and driver unit; and

,

b) managing the use of the cache memory by requesting data transfers only with respect to ones of the plurality of disk drives where data associated therewith is not presently in the cache memory and sending high level commands to the plurality of disk drive controller channels to effect data transfers thereby.

19. The method of claim 18 wherein said apparatus additionally performs the step of:

employing a data semaphore to prevent simultaneous access to the data buffer by a first bus driver and a disk drive interface driver.

20. The method of claim 18 wherein said apparatus additionally performs the steps of:

a) saving a history of data accesses by the host computer;

b) anticipating data accesses from the history of data accesses and retrieving the data associated with the accesses from the disk drives before an actual request therefor is made by the host; and

c) managing the near line archival storage apparatus to create a virtual array, of accessible data including the capacity of the entire near line archival storage apparatus, with the appearance of a disk drive of boundless capacity.

21. The method of claim 18 where a computer system including the host computer and disk drives further includes near line storage apparatus of an automated variety wherein off-line storage media are loaded for reading and writing on request by automated mechanisms so as to avoid the necessity of operator intervention and wherein said apparatus additionally performs the steps of:

employing the host computer operating system communications link to obtain the location of data on the near line storage apparatus from the host computer operating system.

22. The method of claim 21 wherein said apparatus additionally performs the steps of:

a) saving a history of data accesses by the host computer;

b) anticipating data accesses from the history and retrieving the data associated with the accesses from the near line storage apparatus before an actual request therefor is made by the host computer; and

c) managing the near line archival storage apparatus to create a virtual array, of accessible data including the capacity of the entire near line archival storage apparatus, with the appearance of a disk drive of boundless capacity.

23. The disk drive access control apparatus of claim 15 wherein each of said plurality of disk drive controller channels comprises:

a) first bus driver means for connecting to and interfacing with said first bus;

b) disk drive interface driver means for connecting to and interfacing with an associated one of the plurality of disk drives;

c) a data buffer;

d) data semaphore means for preventing simultaneous access to said data buffer by said first bus driver means and said disk drive interface driver means;

e) buffer address register means for providing a current active address into said data buffer;

f) local micro-processor means for controlling said data semaphore means and said disk drive interface driver means; and

,

g) connector means for connecting said local micro-processor means to said second bus.

24. The disk drive access control apparatus of claim 15 and additionally comprising:

computational logic means for using said communications link means to obtain file location information about a data manipulation request from the host computer whereby whereby said host operating system provides transparency about said data file manipulation commands to user programs operating with the host computer and reading and writing data to and from the plurality of disk drives over said host computer link means.

25. The improvement to a computer system of claim 24 wherein:

said computational logic means includes testing logic for testing the plurality of disk drives in a background mode on a time-available basis.

26. The disk drive access control apparatus of claim 24 wherein:

said computational logic means includes learning logic so that once the location of a requested data on the plurality of disk drives has been obtained using said communications link means, it is known and remembered.

27. The disk drive access control apparatus of claim 24 wherein:

a) a computer system including the host computer and disk drives further includes near line archival storage apparatus of an automated variety wherein off-line storage media are loaded for reading and writing on request by automated mechanisms;

b) said computational logic means includes logic for using said communications link means to obtain location information about files on said near line archival storage apparatus; and

c) said computational logic means managing the near line archival storage apparatus to create a virtual array, of accessible data including the capacity of the entire near line archival storage apparatus, with the appearance of a disk drive of boundless capacity.

28. The disk drive access control apparatus of claim 27 wherein additionally:

said computational logic means includes learning logic so that once the location of a requested data on said near line storage apparatus has been obtained using said communications link means, it is known and remembered.

29. The disk drive access control apparatus of claim 28 wherein additionally:

said learning logic of said computational logic means is of a self learning variety which learns through experience so that if a particular file from said near line storage apparatus is repeatedly used at a given time said learning logic learns that from experience and begin loading said file from said near line storage apparatus in anticipation of an expected request so that when said request is made, said file is already read in and available for use.