Remote copy system

• US 8,176,010 B2
• Filed: 03/29/2007
• Issued: 05/08/2012
• Est. Priority Date: 12/03/2003
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Arakawa, Hiroshi, Ninose, Kenta, Asaka, Yoshihiro, Hirakawa, Yusuke
• Primary Examiner(s): Lie, Angela
• Assistant Examiner(s): MACKES, KRIS E
• Application Number:
  US11/727,918
• Publication Number:
  US 20070174352A1
• Time in Patent Office: 1,867 Days
• Field of Search: 707/204, 707/634, 707/687
• US Class Current: 707/634
• CPC Class Codes: G06F 11/2058 using more than 2 mirrored copies
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2074 Asynchronous techniques
• CPC Class Codes: G06F 11/2082 Data synchronisation
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency ensuring consistency in mirrored systems G06F11/2064
• CPC Class Codes: G06F 2201/835 Timestamp
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

In a system in which data employed by a computer is stored in a storage system, the storage system transfers this data to another storage system and a copy of the data is maintained in the other storage system. The consistency of the copy is maintained even when data is written, to the storage system by a computer, without having a write time applied. A source storage system, when a write time is applied to a write request, records the write time and applies this write time to the received write data and, when no write time is applied, applies the recorded write time to the received write data and transfers the write data with this write time applied thereto, to a target storage system. The target storage system stores the write data in a logical volume in the target storage system in accordance with the write time.

Claims

1. A remote copy system comprising:

a plurality of host computers;

a plurality of first storage systems, each comprising a first control section to be coupled to at least one host computer of the plurality of host computers, at least one first logical volume for storing data received from the at least one host computer, and a first storage area for storing data; and

a plurality of second storage systems, each coupled to corresponding ones of the plurality of first storage systems and comprising a second control section, at least one second logical volume for storing a replica of data stored in the first logical volume of a corresponding one of the plurality of first storage systems, and a second storage area for storing data received from the corresponding one of the plurality of first storage systems,

wherein the first control sections of the plurality of first storage systems receive a plurality of write requests from the host computer and store a plurality of write data, which relate to the plurality of write requests, in the first storage areas of the plurality of first storage systems,

wherein the host computer;

(A) sends instructions for deferment of write request processing to all of the first control sections of the plurality of the first storage system,

(B) sends a marker instruction to all of the first control sections after receiving a completion report of the deferment from all of the first control sections,

(C) sends instructions for release of the deferment of the write request processing to all of the first control sections after receiving a completion report of the marker instruction from all of the first control sections, and

repeats the steps of (A), (B), and (C), by incrementing the marker number included in the marker instruction each time the marker instruction is sent,

wherein each of the first control sections transfer the plurality of write data associated with the marker, which is included in the latest marker instruction at the time when it is received, to the corresponding one of the second storage systems,

wherein at least one host computer determines which marker is made at the earliest time among the markers received by all of the second storage systems and instructs all of the second control sections to store the transferred plurality of write data that is previous to the determined marker, and

wherein the each of the second control sections stores the data transferred from the first control section in the corresponding second storage area and restores the data to the second logical volume.

2. The remote copy system according to claim 1,

wherein the at least one host computer which sends instructions for steps (A), (B) and (C) is different from the at least one host computer which instructs all of the second control sections to store the transferred plurality of write data.

3. The remote copy system according to claim 1,

wherein each of the first storage area and the second storage area is a cache memory.

4. The remote copy system according to claim 1,

wherein each of the first storage area and the second storage area formed by one or more logical volumes.

5. The remote copy system according to claim 1,

wherein each of the first control sections associate the write data with a sequential number which is given sequentially to data stored in the corresponding first logical volume before being transferred to the corresponding one of the second storage systems.

6. The remote copy system according to claim 5,

wherein when the data received by each of the second storage systems is not in sequential order, one of the host computers uses the data immediately preceding missing data as received by the second storage systems to determine the marker.

7. The remote copy system according to claim 6,

wherein the second control unit restores the data instructed according to the order of the sequential number to the second logical volume.