STORAGE SYSTEM, AND DATA BACKUP METHOD AND SYSTEM RESTARTING METHOD OF STORAGE SYSTEM

• US 20130097458A1
• Filed: 10/12/2011
• Published: 04/18/2013
• Est. Priority Date: 10/12/2011
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nakayama, Shinichi, Yagisawa, Ikuya, Sekino, Yuta, Nishimoto, Akira
• Granted Patent: US 8,707,096 B2
• Time in Patent Office: Days
• US Class Current: 714/6.3
• CPC Class Codes: G06F 1/263 Arrangements for using multiple switchable power supplies, e.g. battery and AC G06F1/30 takes precedence
• CPC Class Codes: G06F 1/30 Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations for resetting only G06F1/24
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: G06F 11/1658 Data re-synchronization of a redundant component, or initial sync of replacement, additional or spare unit
• CPC Class Codes: G06F 11/2015 Redundant power supplies power supply failure G06F1/30

Abstract

In a storage system for performing data backup using a battery during blackout, when the blackout continues for a long time, problems such as the loss of volatile memory data due to the consumption of battery capacity and the difference in recovery time between controller units after power recovery occur during restarting of the system. The present invention solves the problems by selecting (a1) battery backup or (a2) saving of data in a nonvolatile device based on the battery capacity or setting of modes, and selecting (b1) inhibiting restart of the system or (b2) storing of data in the volatile memory to a nonvolatile memory means and performing access via write-through based on the remaining capacity of the battery when restarting the system after power recovery. Further, the system enables to increase and decrease the volatile memory capacity of the write area and mutually confirms synchronization of controller units and contents of volatile memories. Thereby, the system enables to prevent data loss and inconsistency of data.

Claims

1. A storage system coupled to a computer or a management computer, the storage system comprising one or more controller units, one or more power supply units and one or more battery units, and a drive unit having a plurality of nonvolatile devices;

the controller unit comprising

a control unit;

a volatile memory; and

a nonvolatile memory device;

the power supply unit being coupled to the battery unit and including an external power input unit and a power supply control unit;

wherein when power supply from an exterior is interrupted, the controller unit determines the content of interruption of power supply from the exterior, and based on the determination result and a data backup mode information set via the management computer, selects whether to continue retaining the data stored in the volatile memory in the volatile memory or to store the data in the nonvolatile memory device and retain the data therein.

2. The storage system according to claim 1, wherein when the system selects to retain data in the volatile memory, the system further selects whether to retain the data in the volatile memory or to store the data in the nonvolatile memory device and retain the data therein based on a capacity of the battery.

3. The storage system according to claim 2, wherein the data stored in the volatile memory or the nonvolatile memory device is composed of a management information data and a user data.

4. The storage system according to claim 1, wherein the volatile memory includes a read data storage area for storing a read data read from a plurality of nonvolatile devices and a write data storage area for storing the data written from the computer, and when the system selects to retain data in the volatile memory, a capacity of the write data storage area of the volatile memory is increased or decreased based on the capacity of the battery.

5. The storage system according to claim 4, wherein when the system selects to retain data in the volatile memory, the total capacity of the volatile memory is increased or decreased based on the capacity of the battery.

6. The storage system according to claim 5, wherein a mode for writing data to the write data storage area of the volatile memory is selected between a write-back mode and a write-through mode based on the capacity of the battery.

7. The storage system according to claim 4, wherein whether to inhibit restarting of the storage system or to restart the system and select a write-through mode for the write access to the volatile memory when power supply is resumed is selected.

8. The storage system according to claim 7, wherein after inhibiting restarting of the system or after restarting the system, the remaining capacity of the battery is monitored, and when the capacity exceeds a predetermined threshold, restarting of the system is started or the mode of write access to the volatile memory is changed from the write-through mode to the write-back mode.

9. The storage system according to claim 8, wherein during restarting of the system after power supply is resumed, the following steps are performed:

(1) migrating data from the nonvolatile memory device to the volatile memory;

(2) confirming data consistency by comparing the data in the non-volatile memory device and the data migrated to the volatile memory;

(3) after confirming consistency, deleting the data in the nonvolatile memory device;

(4) storing the management information data in the volatile memory in the nonvolatile device;

(5) shifting the storage system to a normal state; and

(6) storing the user data in the volatile memory to the nonvolatile device and deleting the user data in the volatile memory.

10. The storage system according to claim 8, wherein during restarting of the system after power supply is resumed, the following steps are performed:

(1) migrating data from the nonvolatile memory device to the volatile memory;

(2) confirming data consistency by comparing the data in the non-volatile memory device and the data migrated to the volatile memory;

(3) after confirming consistency, storing the management information data in the volatile memory into the nonvolatile device;

(4) storing the user data in the volatile memory to the nonvolatile device and deleting the user data in the volatile memory; and

(5) deleting the management information data from the volatile memory.

11. The storage system according to claim 9, wherein during restarting of the system after power supply is resumed, the following steps are performed:

(1) checking synchronization of controller units; and

(2) mutually checking contents of the data in the volatile memories of the controller units and matching the data.

12. The storage system according to claim 10, wherein during restarting of the system after power supply is resumed, the following steps are performed:

(1) checking synchronization of control units; and

(2) mutually checking contents of the data in the volatile memories of the control units and matching the data.

13. The storage system according to claim 11, wherein the current battery remaining capacity of the battery, backup available time and the total capacity or the write area capacity of the volatile memory are displayed, and the setting of the data backup mode, the backup time, the write area capacity of the volatile memory and the settings of the restart mode of the storage system or the battery capacity threshold are performed via the management computer.

14. The storage system according to claim 12, wherein the current battery remaining capacity, backup available time and the total capacity or the write area capacity of the volatile memory are displayed and the settings of the data backup mode, the backup time, the write area capacity and the setting of the restart mode of the storage system or the battery capacity threshold are performed via the management computer.

15. A data backup method of an storage system coupled to a computer and a management computer, the system comprising a controller unit composed of a control unit, a volatile memory and a nonvolatile memory device, a power supply unit composed of an external power input unit and a power supply control unit, a battery unit, and a drive unit composed of a plurality of nonvolatile devices, the method comprises:

a step of detecting interruption of power supply from the exterior;

a step of determining the contents of interruption of the power supply from the exterior;

a step of acquiring a backup mode information set via the management computer; and

a step of selecting whether to continue retaining the data stored in the volatile memory in the volatile memory or to store the data in the non-volatile memory device and retain the data therein based on the determination result and the backup mode information.

16. A system restarting method of a storage system coupled to a computer or a management computer, the system comprising a controller unit comprising a control unit, a volatile memory and a nonvolatile memory device, a power supply unit composed of an external power input unit and a power supply control unit, a battery unit, and a drive unit having a plurality of nonvolatile devices, the method comprising:

a step of detecting interruption of power supply from the exterior;

a step of determining the contents of interruption of the power supply from the exterior;

a step of acquiring a backup mode information set via the management computer;

a step of selecting whether to continue retaining the data stored in the volatile memory in the volatile memory or to store the data in the non-volatile memory device and retain the data therein based on the determination result and the backup mode information;

a step of detecting resumption of power supply from the exterior;

a step of checking stored data in the nonvolatile memory device;

a step of storing the stored data in the nonvolatile memory device to the volatile memory and the nonvolatile device;

a step of confirming synchronization of the control units;

a step of mutually confirming contents of the data in the volatile memories of control units; and

a step of matching the contents of the data in the volatile memories.

17. The method for restarting the system according to claim 16, wherein the step of storing the stored data in the nonvolatile memory device to the volatile memory and the nonvolatile device comprises:

(1) a step of migrating data from the nonvolatile memory device to the volatile memory;

(2) a step of confirming data consistency by comparing the data in the nonvolatile memory device and the data migrated to the volatile memory;

(3) a step of deleting the data in the nonvolatile memory device after confirming consistency;

(4) a step of storing the management information data in the volatile memory (cache memory 3207, 3307) into the nonvolatile device (HDD 43);

(5) a step of shifting the storage system to a normal state; and

(6) a step of storing the user data in the volatile memory to the non-volatile device and deleting the user data in the volatile memory.

18. The method for restarting the system according to claim 16, wherein the step of storing the stored data in the nonvolatile memory device to the volatile memory and the nonvolatile device comprises:

(1) a step of migrating data from the nonvolatile memory device to the volatile memory;

(2) a step of confirming data consistency by comparing the data in the nonvolatile memory device and the data migrated to the volatile memory;

(3) a step of storing the management information data in the volatile memory into the nonvolatile device after confirming consistency;

(4) a step of storing the user data in the volatile memory to the non-volatile device and deleting the user data in the volatile memory; and

(5) a step of deleting the management information data from the volatile memory.