Storage apparatus

• US 20050216658A1
• Filed: 05/19/2004
• Published: 09/29/2005
• Est. Priority Date: 03/23/2004
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Takeuchi, Hisaharu, Muto, Yoshiaki
• Granted Patent: US 7,171,517 B2
• Time in Patent Office: Days
• US Class Current: 711/113
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2074 Asynchronous techniques

Abstract

A storage apparatus is provided in which the data amount of transfer data to a secondary disk controller from a primary disk controller at the event of remote copying can be reduced, and data integrity also can be assured. According to the storage apparatus, in the primary disk controller, overwriting update data in same records during a specified time between a preset first base point and a preset second base point on the update data that are stored in the second area of the cache memory and that are to be transferred to the secondary disk controller; and in the secondary disk controller, handling the update data between the first base point and the second base point as real data having consistency.

Claims

1. A storage apparatus comprising:

a primary disk controller including a cache memory and a control memory and to be connected to a host computer;

a disk device connected to the primary disk controller;

a secondary disk controller including a cache memory and a control memory;

a disk device connected to the secondary disk controller;

the cache memory of the primary disk controller having a first area for storing update data that are to be written to the disk device, and a second area for storing update data that are to be transferred to the secondary disk controller;

the primary disk controller providing timestamps and acceptance numbers to update data sent from the host computer so as to be stored into the second area of the cache memory as update data that are to be transferred to the secondary disk controller;

transferring the stored update data to the secondary disk controller; and

performing remote copying to the secondary disk controller;

the primary disk controller overwriting update data in same records during a specified time between a preset first base point and a preset second base point on the update data that are stored in the second area of the cache memory and that are to be transferred to the secondary disk controller; and

the secondary disk controller handling the update data between the first base point and the second base point as real data having consistency.

2. A storage apparatus according to claim 1, wherein:

the timestamps are provided by the host computer or the primary disk controller;

the acceptance numbers are provided by the primary disk controller in accordance with acceptance information in the update data from the host computer; and

these items of information are stored into the control memory.

3. A storage apparatus according to claim 1, wherein:

the first base point and the second base point are synchronized with each other between the primary disk controller and the secondary disk controller.

4. A storage apparatus according to claim 1, wherein:

when update data in a same record is updated on the update data stored in the cache memory of the primary disk controller, information of the number of overwrites for the update data is stored in the control memory; and

in the secondary disk controller, the update data is verified in accordance with the information of the timestamp, the acceptance number, and the number of overwrites.

5. A storage apparatus according to claim 1, wherein:

in the primary disk controller, the second base point is stored as an synchronization point into the cache memory of the primary disk controller; and

in the secondary disk controller, update data between the first base point and the synchronization point is handled as real data having consistency.

6. A storage apparatus according to claim 5, wherein:

the synchronization point is stored into the cache memory of the primary disk controller in response to a synchronization request from the host computer.

7. A storage apparatus according to claim 1, wherein:

the primary disk controller transfers in batch the update data between the first base point and the second base point to the secondary disk controller.

8. A storage apparatus according to claim 1, wherein:

a mode for overwriting and a mode for not overwriting update data in a same record on update data stored in the cache memory of the primary disk controller are provided;

upon acceptance of a mode switching instruction from the host computer, mode switching information is stored into the cache memory of the primary disk controller; and

the mode switching information is transferred to the secondary disk controller; and

in the secondary disk controller, a operation mode is changed in accordance with the mode switching information transferred from the primary disk controller.

9. A storage apparatus according to claim 8, wherein:

a plurality of the primary disk controllers are provided, and the mode switching information is transferred from each of the plurality of primary disk controllers to the secondary disk controller; and

in the secondary disk controller, the operation mode is changed when all the mode switching information transferred from the plurality of primary disk controllers conform to one another.

10. A storage apparatus according to claim 8, wherein:

the mode switching information is stored into the cache memory of the primary disk controller in accordance with a processing state of the update data in the primary disk controller.

11. A storage apparatus comprising:

a primary disk controller including a cache memory, a control memory, a primary write-data accepting section, a primary write-data transmitting section, and a disk-data transmission/reception section and connected to a host computer;

a disk device connected to the disk-data transmission/reception section of the primary disk controller;

a secondary disk controller including a cache memory, a control memory, a secondary write-data accepting section, and a disk-data transmission/reception section;

a disk device connected to the disk-data transmission/reception section of the secondary disk controller;

the cache memory of the primary disk controller having a first area for storing update data that are to be written by the disk-data transmission/reception section to the disk device, and a second area for storing update data that are to be transferred to the secondary disk controller;

the primary disk controller accepting update data from the host computer through primary write-data accepting section;

providing timestamps and acceptance numbers to the update data sent from the host computer so as to be stored into the second area of the cache memory as update data that are to be transferred to the secondary disk controller;

transferring the stored update data to the secondary disk controller through the primary write-data transmitting section; and

performing remote copying to the secondary disk controller;

the primary disk controller overwriting update data in same records during a specified time between a preset first base point and a preset second base point on the update data that are stored in the second area of the cache memory and that are to be transferred to the secondary disk controller, and storing the overwritten data into the cache memory of the primary disk controller with the second base point being used as a synchronization point; and

the secondary disk controller accepting through the secondary write-data accepting section the update data transferred from the primary write-data transmitting section, storing the accepted update data into the cache memory of the secondary disk controller, and handling the stored update data between the first base point and the synchronization point as real data having consistency.