STORAGE DEVICE

• US 20100180068A1
• Filed: 07/04/2007
• Published: 07/15/2010
• Est. Priority Date: 08/09/2006
• Status: Active Grant

• Current Assignee: Hitachi ULSI Systems Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi ULSI Systems Company Limited (Hitachi, Ltd.)
• Inventors: Matsumoto, Masahiro, Makuni, Kazuki, Azuma, Shuichiro, Koike, Yasuyuki, Takemura, Shigeru, Okinaga, Takayuki
• Granted Patent: US 8,205,034 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7211 Wear leveling
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

Abstract

A storage device realizing an improvement in rewrite endurance of a nonvolatile memory and an improvement in data transfer rate of write and read is provided including a nonvolatile memory 101; a volatile memory 106 for storing file management information of the nonvolatile memory 101; a controller 103 for controlling the nonvolatile memory 101 and the volatile memory 106; and a power supply maintaining unit 105 for supplying power to the nonvolatile memory 101, the volatile memory 106, or the controller 103 upon power shutdown. The controller 103 reads the file management information in the nonvolatile memory 101 upon power-on and writes the same in the volatile memory 106, and read and write operations are performed based on the file management information in the volatile memory 106, and the file management information in the volatile memory 106 is written in the nonvolatile memory 101 upon power shutdown.

Claims

1. A hard-disk-drive compatible storage device connected to a host for use, the storage device comprising:

a semiconductor nonvolatile memory having a file management information section and a data section and configured to save data sent from a host in the data section and save file management information relevant to saving the data in the file management information section;

a volatile memory;

a controller for performing control on write and read of data with the host under control of the host; and

a power supply maintaining unit, wherein

the storage device is configured to be driven with electric power supplied from the host, and

the controller is configured to;

(1) manage the write and read of the data exchanged with the host by a data management system compatible with a data management system for hard disks;

(2) read file management information from the file management information section in the nonvolatile memory and write the same in the volatile memory upon startup of the host;

(3) perform read and write based on the file management information in the volatile memory, and at the same time, update the file management information within the volatile memory when a read operation and a operation from the host to the nonvolatile memory are observed;

(4) perform allocation of destinations to save the data so that the data is saved in the volatile memory when the data sent from the host matches a condition set in advance with respect to at least either of a data size, a rewriting frequency, or a vacancy ratio by block, and the data is saved in the nonvolatile memory when the data sent from the host does not match the condition set in advance;

(5) read the updated file management information recorded in the volatile memory and write the same in the nonvolatile memory corresponding to an end operation in the host; and

(6) switch power supply to the power supply maintaining unit and also performs control on cutting off a signal from the host when unexpected power shutdown occurs on the host side, and read the updated file management information recorded in the volatile memory and write the same in the nonvolatile memory with using electric power supplied from the power supply maintaining unit.

2. The storage device according to claim 1, wherein

the power supply maintaining unit is provided with a capacitor, and

deterioration of the capacitor is detected by a change in a voltage flown into the capacitor or a potential difference of the capacitor.

3. The storage device according to claim 1, wherein

the nonvolatile memory comprises a plurality of nonvolatile memory devices;

data storage addresses for in a case of emergency power shutdown are separately assigned to the plurality of nonvolatile memory devices in advance; and

,

upon emergency power shutdown, the controller reads data in the volatile memory and writes the same in respective data storage addresses in the plurality of nonvolatile memory devices.

4. The storage device according to claim 1, wherein

the controller reads data having a high rewriting frequency in the data section in the nonvolatile memory upon power-on and writes the same in the volatile memory.

5. The storage device according to claim 1, wherein

the file management information comprises at least one or more of non-defective/defective product information, a logical address, an in-chip address, a number of rewrite cycles, ECC information, location information of data, and a defect occurrence history.

6. The storage device according to claim 1, wherein

the controller writes writing data in the nonvolatile memory when a size of the writing data is larger than a first size, and writes the writing data in the volatile memory when the size of the writing data is smaller than the first size in a write operation.

7. The storage device according to claim 1, wherein

the controller writes, when a rewriting frequency of writing data is larger than a first frequency, the writing data in the volatile memory, and writes, when the rewriting frequency of the writing data is smaller than the first frequency, the writing data in the nonvolatile memory in a write operation.

8. The storage device according to claim 1, wherein

the controller writes data in the volatile memory when a vacancy ratio in block unit is larger than a first vacancy ratio, and writes data in the nonvolatile memory when the vacancy ratio in block unit is smaller than the first vacancy ratio in a write operation.

9. The storage device according to claim 1, wherein

the controller judges a number of rewrite cycles based on the file management information in the volatile memory and performs an equalization process on the nonvolatile memory.

10. The storage device according to claim 1, wherein

the controller performs an addition to a free page in page unit in one block in the nonvolatile memory, and updates the file management information in the volatile memory in a write operation.

11. The storage device according to claim 1, wherein

the power supply maintaining unit is provided with a capacitor, and

the capacitor is sandwiched between a substrate and a spacer to be fixed.

12. The storage device according to claim 11, wherein

a material of the spacer is either of a liquid crystal resin, polycarbonate, or a non-conductive material.

13. The storage device according to claim 1, wherein

a lifetime is detected according to a remaining number of remaining blocks.

17. The storage device according to claim 1, wherein

the process carried out by the controller includes a process to erase the file management information recorded in the nonvolatile memory, and write the updated file management information recorded in the volatile memory in the nonvolatile memory upon startup.

14. A hard-disk-drive compatible storage device connected to a host for use, the storage device comprising:

a semiconductor nonvolatile memory having a storage capacity of at least 16 Gbits and having a file management information section and a data section and configured to store data sent from the host in the data section and store file management information relevant to the data storage in the file management information section;

a volatile memory;

a controller for performing control on write and read of data with the host under control of the host; and

a power supply maintaining unit including an electric double-layer capacitor having a capacity of at least 0.1 F, wherein

the storage device is configured such that write and read of the data exchanged with the host via a hard-disk-drive compatible interface are connected to the host, and when the host is under a normal operation, the semiconductor nonvolatile memory, the volatile memory, and the controller are driven by electric power supplied by the host, and the electric double-layer capacitor is charged by the electric power supplied by the host, and

the controller is configured to;

(1) read file management information from the file management information section in the nonvolatile memory and write the same in the volatile memory in response to startup of the host;

(2) perform read and write based on the file management information in the volatile memory, and at the same time, update the file management information within the volatile memory when an access of read or write from the host to the storage device is observed;

(3) perform allocation of destinations to save the data sent from the host either in the volatile memory or in the nonvolatile memory based on a condition set in advance;

(4) read the updated file management information recorded in the volatile memory and write the same in the nonvolatile memory in response to an end operation in the host; and

(5) switch power supply to the power supply maintaining unit and controls to cut off a signal from the host when an unexpected power shutdown occurs on the host side, and read the updated file management information recorded in the volatile memory and write the same in the nonvolatile memory with using electric power supplied from the power supply maintaining unit.

16. The storage device according to claim 14, wherein

the condition set in advance is set for either of a data size, a rewriting frequency, or a vacancy ratio in block unit.

15. A hard-disk-drive compatible storage device connected to a host for use, the storage device comprising:

a semiconductor nonvolatile memory having a storage capacity of at least 16 Gbits and having a file management information section and a data section and configured to store data sent from the host in the data section and store file management information relevant to the data storage in the file management information section;

a volatile memory having a memory capacity to save the file management information and at least data that match a condition set in advance;

a controller for performing control on write and read of data with the host under control of the host; and

a power supply maintaining unit including an electric double-layer capacitor having a capacity of at least 0.1 F, wherein

the storage device is configured such that write and read of the data exchanged with the host via a hard-disk-drive compatible interface are connected to the host, and when the host is under a normal operation, the semiconductor nonvolatile memory, the volatile memory, and the controller are driven by electric power supplied by the host, and the electric double-layer capacitor is charged by the electric power supplied by the host, and

the controller is configured to;

(1) read file management information from the file management information section in the nonvolatile memory and write the same in the volatile memory in response to startup of the host;

(2) perform read and write based on the file management information in the volatile memory, and at the same time, update the file management information within the volatile memory when an access of read or write from the host to the storage device is observed;

(3) perform allocation of destinations to save the data sent from the host either in the volatile memory or in the nonvolatile memory based on the condition set in advance;

(4) read the updated file management information recorded in the volatile memory and write the same in the nonvolatile memory in response to an end operation in the host; and

(5) switch power supply to the power supply maintaining unit and controls to cut off a signal from the host when an unexpected power shutdown occurs on the host side, and read the updated file management information recorded in the volatile memory and write the same in the nonvolatile memory with using electric power supplied from the power supply maintaining unit.