External storage control device and data transfer method between external storage control devices

• US RE43,600 E1
• Filed: 07/09/2003
• Issued: 08/21/2012
• Est. Priority Date: 01/10/1996
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ozawa, Koji, Sano, Kazuhide, Nakamura, Katsunori, Koide, Takeshi
• Primary Examiner(s): PEUGH, BRIAN R
• Application Number:
  US10/614,808
• Time in Patent Office: 3,331 Days
• Field of Search: None
• US Class Current: 711/112
• CPC Class Codes: G06F 2003/0692 digital I/O from or to direct access storage devices, e.g. magnetic, optical, magneto-optical disc
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

In a data processing system in which main and sub disk storage devices are under the control of individual each disk control devices, the write processing time is reduced by selectively sending data according to the command-chaining time between main and sub disk control devices. A section for judging cable length and function of the sub disk control device 36 estimates command-chaining time between a pair of main and sub disk storage devices. The channel command analyzing section 31 estimates the number of records to be transferred and the length of a record using a LOCATE RECORD command. The command judgment section for the sub disk control device 32 optimizes the command-chain to be issued to the sub disk control device using the above-mentioned information. Then, the section for issuing command to the sub disk control device 35 issues the optimized command chain. Thus, a shorter transmission time is realized by either sending individual records or an entire track of data.

Claims

1. A first external storage control device which is connected to a first group of external storage devices and controls data transfer between said first group of external storage devices and a host, wherein

said first external storage control device is connected to a second external storage control device which is connected to a second group of external storage devices;

said first external storage control device being equipped with a storing means that stores write data transferred by a write command from the host and means that transfers the write data stored in said storing means to the second external storage control device according to a write command;

the first external storage control device also having means for storing the write data to both an external storage device belonging to said first group of external storage devices and to an external storage device belonging to said second group of external storage devices;

means for estimating the command-chaining time between said first and second external storage control devices;

means for estimating a time for a write process, including said estimated command-chaining time, to one of said second group of external storage devices; and

command means for writing data in the write process in a single operation;

wherein in a case where said first external storage

control device has received plural write commands for said data from the host, said first external storage control device transfers said write data to said second external storage control device by selecting a transfer method with the shortest processing time;

said transfer method with the shortest processing time is selected by considering the command-chaining time between said first external storage control device and said second external-storage control device; and

said means for estimating a time for a write process estimates the time before starting the write process to said second external storage control device according to said selected transfer method.

2. A first external storage control device according to claim 1, wherein said means for estimating the command-chaining time estimates according to one of (a) measuring the command-chaining time between a specified command to the next command and (b) setting a length of interface cable between the first and second external storage control devices in advance.

3. A first external storage control device according to claim 1, wherein said means for estimating the command-chaining time estimates the command-chaining time by measuring the time for two command chains.

4. A first external storage control device which is connected to a first group of external storage devices and to a second external storage control device, and which controls data transfer between said external storage devices and a host, wherein,

the second external storage control device is connected to a second group of external storage devices, and controls data transfer between said second group of external storage devices and the host,

said first external storage control device being equipped with a storing means that stores write data transferred through a write command from the host, a first transfer means to transfer write data to said second external storage control device for each of plural write commands received from the host, and a second transfer means which transfers write data from the host to the second external storage control device for each of plural write commands received from the host by using only one write command, and

the first external storage control device also including means for calculating processing time for data transfer between said first external storage control device and said second external storage control device using said first transfer means and using said second transfer means, means to compare said two processing times and for storing the same data to an external storage device belonging to said first and second group of external storage devices;

wherein when said first external storage control device has received plural write data commands from the host, the external storage control device transfers data from said first external storage control device to said second external storage control device, using a transfer means having the smaller processing time according to the result of said comparing means; and

wherein said transfer means having the smaller processing time is selected by considering the command-chaining time between said first external storage control device and said second external storage control device.

5. A first external storage control device according to claim 4, further comprising:

means for estimating the command-chaining time between said first and second external storage control devices; and

means for estimating a time for a write process, including said estimated command-chaining time, to one of said second group of external storage devices, before starting the write process to said second external storage control device according to said selected transfer means.

6. A first external storage control device according to claim 5, wherein said means for estimating the command-chaining time estimates according to one of (a) measuring the command-chaining time between a specified command to the next command and (b) setting a length of interface cable between the first and second external storage control devices in advance.

7. A first external storage control device according to claim 5, wherein said means for estimating the command-chaining time estimates the command-chaining time by measuring the time for two command chains.

8. A first external storage control device which is connected to a first group of external storage devices and a host processor, and which controls data transfer between said first group of external storage devices and said host processor, wherein

said first external storage control device is connected to a second external storage control device that exists a large distance away from said first external storage control device, and which is connected to a second group of external storage devices;

said first external storage control device is equipped with a buffer memory that stores write data transferred by a write command from said host processor and with a function that transfers said write data stored in said buffer memory to said second external storage control device according to the write command;

said first external storage control device has a function to store said write data to one of said external storage devices in said first group and to one of said external storage devices in said second group;

wherein if said first external storage control device has received plural write commands for said data from said host processor, said first external storage control device transfers said write data to said second external storage control device by selecting a transfer method with the shortest processing time; and

wherein said transfer method with the shortest processing time is selected by considering the command-chaining time between said first external storage control device and said second external storage control device.

9. A first external storage control device according to claim 8, further comprising:

means for estimating the command-chaining time between said first and second external storage control devices;

means for estimating a time for a write process, including said estimated command-chaining time, to one of said second group of external storage devices, before starting the write process to said second external storage control device according to said selected transfer method; and

command means for writing data in the write process in a single operation.

10. A first external storage control device according to claim 9, wherein said means for estimating the command-chaining time estimates according to one of (a) measuring the command-chaining time between a specified command to the next command and (b) setting a length of interface cable between the first and second external storage control devices in advance.

11. A first external storage control device according to claim 9, wherein said means for estimating the command-chaining time estimates the command-chaining time by measuring the time for two command chains.

12. A storage system comprising:

a first plurality of disk drives; and

a disk controller connected to a host processor and said first plurality of disk drives, said disk controller controlling data write from said host processor to said first plurality of disk drives, and data transfer from said first plurality of disk drives to said host processor;

wherein said disk controller is arranged to be connected to another disk controller, and to obtain information on a support function of the another disk controller.

13. A storage system according to claim 12, wherein said disk controller includes means for obtaining the information on the support function of the another disk controller from the another disk controller.

14. A storage system according to claim 13, wherein said disk controller establishes a pair of disk drives, said pair including one of said first plurality of disk drives and one of a second plurality of disk drives which are controlled by the another disk controller;

and

wherein said obtaining means obtains the information on the support function of the another disk controller from the another disk controller when said pair of disk drives is established.

15. A storage system according to claim 12, wherein said disk controller includes a management table for storing the information on the support function of the another disk controller.

16. A storage system according to claim 15, wherein said disk controller further includes means for obtaining the information on the support function of the another disk controller from the another disk controller.

17. A storage system according to claim 16, wherein said disk controller establishes a pair of disk drives, said pair including one of said first plurality of disk drives and one of a second plurality of disk drives which are controlled by the another disk controller;

and

wherein said obtaining means obtains the information on the support function of the another disk controller from the another disk controller when said pair of disk drives is established.

18. A storage system according to claim 16, wherein said disk controller stores the information on the support function of the another disk controller, which information is obtained from the another disk controller by said obtaining means, in said management table.

19. A storage system according to claim 12, wherein said disk controller controls issuance, to the another disk controller, of information that is different according to the support function of the another disk controller.

20. A storage system according to claim 19, wherein said disk controller performs a control according to a first support function of the another disk controller if the another disk controller has the first support function.

21. A storage system according to claim 19, wherein said disk controller controls issuance, to the another disk controller, of information that does not correspond to a second support function, if the another disk controller does not have the second support function.

22. A storage system according to claim 19, wherein said disk controller includes a function determining section for judging the support function of the another disk controller.

23. A storage system according to claim 22, wherein said disk controller includes a management table for storing the information on the support function of the another disk controller.

24. A storage system according to claim 23, wherein said disk controller further includes means for obtaining the information on the support function of the another disk controller from the another disk controller.

25. A storage system according to claim 24, wherein said disk controller establishes a pair of disk drives, said pair including one of said first plurality of disk drives and one of a second plurality of disk drives which are controlled by the another disk controller;

and

wherein said obtaining means obtains the information on the support function of the another disk controller from the another disk controller when said pair of disk drives is established.

26. A storage system according to claim 24, wherein said disk controller stores the information on the support function of the another disk controller, which information is obtained from the another disk controller by said obtaining means, in said management table.

27. A storage system according to claim 26, wherein said function determining section judges the support function of the another disk controller in accordance with the information on the support function of the another disk controller in said management table.

28. A storage system according to claim 19, wherein said disk controller does not issue a specified command to the another disk controller, if said disk controller judges from the information on the support function of the another disk controller that the another disk controller does not accept the specified command.

29. A storage system comprising:

a first plurality of disk drives; and

a disk controller connected to a host processor and said first plurality of disk drives, said disk controller controlling data transfer from said first plurality of disk drives to said host processor;

wherein said disk controller is connected to another storage system, and said disk controller transfers a read command, received from the host processor, to the another storage system, in the case where object data for the read command exists in the another storage system,

wherein said disk controller controls data write from said host processor to said first plurality of disk drives, and

wherein said disk controller confirms that object data for the read command or a write command received from the host processor exists in the another storage system, and transfers the read command or the write command to the another storage system.