Storage subsystem and storage system

• US 20050210210A1
• Filed: 03/17/2005
• Published: 09/22/2005
• Est. Priority Date: 03/22/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nagata, Koji, Arai, Koji
• Granted Patent: US 7,343,449 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 11/2074 Asynchronous techniques
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

The first storage subsystem, when new data is written in a first memory device beyond a certain timing, writes pre-updated data prior to update by said new data into a pre-updated data memory region and, in addition, updates snapshot management information that expresses a snapshot of a data group within the first memory device to information that expresses the snapshot at the certain timing and, at a later timing than the certain timing, judges, on the basis of the snapshot management information, in which of either the pre-updated data memory region or the first memory device the data constituting the data group at a certain timing exists, acquires data from the one in which the data exists and writes it into the second memory device of the second storage subsystem, and generates the certain timing repeatedly.

Claims

1. A storage subsystem of a storage system that comprises a first storage subsystem comprising a first memory device and a second storage subsystem comprising a second memory device,

wherein the first storage subsystem can be communicably connected to a host device for sending write target data and to said second storage subsystem, and comprises:

means for writing write target data from said host device in said first memory device;

a snapshot memory region for the memory of snapshot management information that expresses a snapshot of a data group within said first memory device;

a pre-updated data memory region for storing data that constitutes data prior to update by the write target data and constitutes data that has been written in said first memory device;

pre-updated data write means for, beyond a certain timing and when write target data has been written in said first memory device, writing said pre-updated data in said pre-updated data memory region;

snapshot updating means for, beyond said certain timing and when write target data has been written in said first memory device, updating said snapshot management information to information that expresses said snapshot at said certain timing;

remote copy means for, at a later timing than said certain timing, judging, on the basis of the snapshot management information updated at said later timing, in which of either said pre-updated data memory region or said first memory device the data constituting said data group at said certain timing exists and, by acquiring and sending the data from the one in which the data exists to said second storage subsystem, constructing said data group at said certain timing in said second memory device; and

timing generating means for repeatedly generating said certain timing.

2. The storage subsystem according to claim 1 further comprising means for, when said certain timing has been generated again, deleting all pre-updated data stored in said pre-updated data memory region.

3. The storage subsystem according to claim 1 wherein said pre-updated data memory region is a third memory device that can be configured as a pair with said first memory device,

said first storage subsystem comprises local copy means for, in a case where the pair state of said first memory device and said third memory device is a first state, writing the write target data in not only said first memory device but also said third memory device, and

said timing generating means repeatedly generates said certain timing by making said pair state a second state.

4. The storage subsystem according to claim 3 wherein said first storage subsystem comprises:

a first type logical volume, provided in a physical memory device, for which no specific attributes are set;

a plurality of second type logical volumes, provided in a physical memory device, for which specific attributes are set, and

said first memory device and said second memory device constitute said first type logical volume,

said third memory device constitutes a virtual logical volume configured from at least one of the second type logical volumes,

and said local copy means, by writing said write target data in a second type logical volume of said plurality of second type logical volumes that has a free space, writes said write target data in said virtual logical volume.

5. The storage subsystem according to claim 1 wherein said first storage subsystem comprises a cache memory for the temporary memory of said write target data exchanged between said host device and said first memory device, and

said pre-updated data memory region is provided in said cache memory.

6. The storage subsystem according to claim 1, wherein said pre-updated data memory region is provided in the first memory device.

7. The storage subsystem according to claim 1 wherein said first storage subsystem comprises a cache memory for the temporary memory of said write target data exchanged between said host device and said first memory device, and

all or part of said snapshot management information is stored in at least one of said cache memory and the first memory device.

8. The storage subsystem according to claim 1 wherein said first storage subsystem comprises:

a cache memory for the temporary memory of said write target data exchanged between a host device for sending write requests and write target data and said first logical volume;

at least one computer;

and a program memory region in which one or more computer programs are stored for, by being read by said at least one computer, actuating said at least one computer,

said pre-updated data memory region is provided on said cache memory, and

said at least one computer which read said one or more computer programs;

(1) receives write requests and write target data from said host device;

(2) writes said received write target data in said first memory device in accordance with said received write requests;

(3) from said certain timing onward, in addition to the processing of said (2), every time said processing of (1) is implemented, repeats (4) to (7) below;

(4) writes said pre-updated data in said cache memory;

(5) updates said snapshot management information to information that expresses said snapshot at said certain timing in accordance with the updating of said first memory device by the writing of said write target data in said first memory device;

(6) at a later timing than said certain timing, judges, on the basis of the snapshot management information updated at said later timing, in which of either said cache memory or said first memory device the data constituting said data group at said certain timing exists and, by the acquisition and sending of the data from the one in which the data exists to said second storage subsystem, constructs said data group at said certain timing in said second memory device; and

(7) repeatedly generates said certain timing.

9. The storage subsystem according to claim 8,

wherein said at least one computer deletes all pre-updated data from said cache memory when said certain timing occurs again.

10. The storage subsystem according to claim 9,

wherein said timing generating means regularly or irregularly execute events for the generating of the certain timing.

11. A storage subsystem of a storage system comprising a first storage subsystem comprising a first memory device and a second storage subsystem comprising a second memory device,

wherein said first storage subsystem can be communicably connected to a host device for sending write target data and said second storage subsystem, and comprises:

means for writing write target data from said host device into said first memory device;

a snapshot memory region for the memory of snapshot management information that expresses a snapshot of a data group within said first memory device;

a pre-updated data memory region for storing data that constitutes data prior to update by the write target data and constitutes data that has been written in said first memory device;

pre-updated data write means for, beyond a certain timing when write target data is written in said first memory device, writing said pre-updated data in said pre-updated data memory region;

snapshot updating means for, beyond said certain timing when the write target data is written in said first memory device, updating said snapshot management information to information that expresses said snapshot at said certain timing;

remote copy means for, at a later timing than said certain timing, judging, on the basis of the snapshot management information updated at said later timing, in which of either said pre-updated data memory region or said first memory device the data constituting said data group at said certain timing exists and, acquiring and sending the data from the one in which data exists to said second storage subsystem; and

timing generating means for repeatedly generating said certain timing,

wherein said second storage subsystem comprises means for, by the writing of data received from said first storage subsystem into said second memory device, constructing said data group at said certain timing in said second memory device.

12. The storage subsystem according to claim 11 wherein said second storage subsystem comprises:

a separate snapshot memory region for the memory of separate snapshot management information that expresses a snapshot of a data group within said second memory device;

a separate pre-updated memory region for the memory of separate pre-updated data that constitutes data prior to update by the data from said first storage subsystem and constitutes data that has been written in said second memory device;

pre-updated data write means for, when data from said first storage subsystem is written in said second memory device, writing said separate pre-updated data in said separate pre-updated memory region; and

separate snapshot updating means for, when the data from said first storage subsystem is written in said second memory device, updating said snapshot management information.

13. A storage control method implemented in a storage system that comprises a first storage subsystem comprising a first memory device and a second storage subsystem comprising a second memory device,

wherein, when said first storage subsystem can be communicably connected to a host device for sending write target data, and said second storage subsystem, and comprises:

a snapshot memory region for the memory of snapshot management information that expresses a snapshot of a data group within said first memory device; and

a pre-updated data memory region for storing data that constitutes data prior to update by the write target data and constitutes data that has been written in said first memory device,

the storage control method comprises the steps of;

beyond a certain timing, writing write target data sent from said host device into said first memory device;

beyond said certain timing and when the write target data is written in said first memory device, writing said pre-updated data of said write target data in said pre-updated memory region;

beyond said certain timing and when the write target data is written in said first memory device, updating the snapshot management information to information that expresses said snapshot at said certain timing;

at a later timing than said certain timing, judging, on the basis of the snapshot management information updated at said later timing, in which of either said pre-updated data memory region or said first memory device the data constituting said data group at said certain timing exists and, by the acquisition and sending of the data from the one in which the data exists to said second storage subsystem, constructing said data group at said certain timing in said second memory device; and

repeatedly generating said certain timing.