External storage control device and data transfer method between external storage control devices
Inactive Publication Date: 2012-08-21
HITACHI LTD
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Benefits of technology
[0009]Thus, one purpose of the present invention is to optimize the write process time for the sub external storage control device by taking into consideration the command-chaining time between main and sub external storage control devices. As a result, the present invention offers a means for achieving excellent performance even under the conditions explained above.
[0014]Also, the external storage control device according to the present invention is equipped with means to confirm that the object data exists in the data buffer of another external storage control device in order to transfer data from the data buffer within the external storage control device to an external storage control device that receives the write commands, in addition to data transfer means as mentioned above. Moreover, the processing time can be further reduced by transferring all the physical data together, including the control byte and the check byte in the data buffer.
[0015]Additionally, in the case where object data for the read command, received from the host, exists in the buffer of an external storage control device other than the external storage control device which has received the read command, the processing time for performing a read-out can be shortened by transferring these data to the external storage control device which received the read command instead of accessing the other external storage device.
Problems solved by technology
Further, in case data is duplicated by adopting the system described above, the distance between main and sub external storage control devices becomes large considering the back-ups necessary in case of a disaster.
Method used
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[0024]The preferred embodiments of the present invention will now be described in conjunction with the Figures. FIG. 1 illustrates a configuration diagram of a data processing system according to an embodiment of the present invention. This data processing system includes a main memory device 1, a channel device 2, a backup system 6 and a channel device 7. This data processing system also includes a main disk control device 3 equipped with a buffer memory 4, and a main disk storage device 5, and also includes a sub disk control device 8 equipped with a buffer memory 9, and a sub disk storage device 4. The channel device 2 is connected to the main disk storage control device 3 through an interface cable 11, the main disk storage control device 3 is connected to the sub disk storage control device 8 through an interface cable 12. Interface cables are also used to interconnect other elements shown in this Figure. Preferably, optical fiber cables are used as the interface cables.
[0025]A...
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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.
Description
[0001]This is a continuation application of U.S. Ser. No. 09 / 375,357 filed Aug. 17, 1999, now U.S. Pat. No. 6,321,292, which is a divisional application of U.S. Ser. No. 08 / 779,471 filed Jan. 8, 1997, now U.S. Pat. No. 5,978,890 issued Nov. 2, 1999. The entire contents of these prior applications are hereby incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to an external storage control device which stores data to an external storage device according to a write command from a host. In particular, the present invention relates to a system in which the same data is copied to another external storage device.BACKGROUND OF THE INVENTION[0003]When data used in a host are stored to plural external storage devices, main and sub external storage devices that hold the same data are sometimes provided under individual external storage control devices. In this case, these external storage control devices are mutually connected, and the main external stor...
Claims
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Login to View More IPC IPC(8): G06F12/00G06F13/10G06F3/06G06F12/16G06F13/12
CPCG06F2003/0697G06F3/0601G06F3/0613G06F3/065G06F3/0659G06F3/067G06F3/0673G06F3/0689
InventorOZAWA, KOJISANO, KAZUHIDEKOIDE, TAKESHINAKAMURA, KATSUNORI
OwnerHITACHI LTD