Data-Retention Controller/Driver for Stand-Alone or Hosted Card Reader, Solid-State-Drive (SSD), or Super-Enhanced-Endurance SSD (SEED)

• US 20160070474A1
• Filed: 11/09/2015
• Published: 03/10/2016
• Est. Priority Date: 06/18/2008
• Status: Active Grant

• Current Assignee: Super Talent Technology, Corporation
• Original Assignee: Super Talent Technology, Corporation
• Inventors: Yu, Frank, Ma, Abraham C., Chen, Shimon
• Granted Patent: US 9,720,616 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/1408 by using cryptography for digital transmission H04L9/00
• CPC Class Codes: G06F 13/4282 on a serial bus, e.g. I2C bus, SPI bus on daisy chain buses G06F13/4247
• CPC Class Codes: G06F 2212/401 Compressed data
• CPC Class Codes: G06F 2212/7203 Temporary buffering, e.g. using volatile buffer or dedicated buffer blocks
• CPC Class Codes: G06F 2212/7208 Multiple device management, e.g. distributing data over multiple flash devices
• CPC Class Codes: G06F 2212/7211 Wear leveling
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0685 Hybrid storage combining heterogeneous device types, e.g. hierarchical storage, hybrid arrays
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays
• CPC Class Codes: G11C 11/5678 using amorphous/crystalline phase transition storage elements
• CPC Class Codes: G11C 13/0004 comprising amorphous/crystalline phase transition cells
• CPC Class Codes: G11C 16/349 Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles
• CPC Class Codes: G11C 29/765 in solid state disks

Abstract

A Green NAND SSD Driver (GNSD) driver executes on a host to increase data-retention of flash memory attached to a Super Enhanced Endurance Device (SEED) or Solid-State Drive (SSD). Host accesses to flash are intercepted by the GNSD driver using upper and lower-level filter drivers. A retention-check timer causes a retention routine to be periodically executed. The routine sends high-level commands to the SEED that causes the SEED to refresh either all data or just data blocks with older write dates. Data is refreshed by moving to a new physical block. The retention routine can track write dates of logical blocks and command a SSD to move logical blocks with older write dates. A retention card has a controller that performs the retention routine when not connected to a host, while a SEED power card allows the SEED to refresh data when no host is attached to the SEED.

Claims

1. A Green NAND SSD Driver (GNSD) driver for executing on a host computer comprising:

a retention-check timer that indicates when a retention-check period of time has elapsed;

a retention manager that is periodically activated by the retention-check timer, the retention manager ensuring that flash data is moved to a new flash block before a data-retention time has elapsed, wherein flash data is subject to loss when the data-retention time is exceeded, the retention manager sending commands to a flash drive to perform retention operations to write flash data; and

a plurality of interfaces to peripheral devices that include the flash drive.

2. The GNSD driver of claim 1 wherein the plurality of interfaces include internal interfaces and external interfaces, wherein the external interfaces comprise at least two of:

a Serial AT-Attachment (SATA) bus, a Peripheral Components Interconnect Express (PCIe) bus, a compact flash (CF) bus, a Universal-Serial-Bus (USB), a Non-Volatile-Memory NVMe bus, a Firewire 1394 bus, a Fibre Channel (FC) bus, and a Thunderbolt bus;

and wherein the internal interfaces comprise at least two of;

a Serial AT-Attachment (SATA) bus, an Integrated Device Electronics (IDE) bus, a Peripheral Components Interconnect Express (PCIe) bus, a compact flash (CF) bus, a Universal-Serial-Bus (USB), and a Secure Digital (SD) bus.

3. The GNSD driver of claim 1 further comprising:

wherein the flash drive is a Super Enhanced Endurance Device (SEED);

a vendor command sent by the retention manager to the SEED, the vendor command causing the SEED to perform a retention operation that moves physical blocks of flash data having a write date before a target write date to ensure data retention.

4. The GNSD driver of claim 3 wherein the vendor command causes the SEED to move all physical blocks of data without regard to write dates.

5. The GNSD driver of claim 3 wherein the vendor command causes the SEED to perform a retention routine that reads a write date for each physical block and moves the physical block when the write date is earlier than a trigger date while not moving physical blocks having write dates after the trigger date,

whereby the SEED selectively moves physical blocks based on write dates to ensure data retention.

6. The GNSD driver of claim 3 wherein when the host computer is disconnected or powered down, the SEED periodically powers up after a SEED retention-check time elapses, the SEED executing the retention operation to ensure flash data retention when the host computer is disconnected or powered down.

7. The GNSD driver of claim 3 wherein the vendor command causes the SEED to move a block at a single physical block address to a new physical block address.

8. The GNSD driver of claim 1 further comprising:

wherein the flash drive is a non-SEED Flash Drive;

the retention manager will create an retention file of write date of all directories/subdirectories and files based on the file system, and store it to the flash drive if not existed;

wherein the retention manager will manage the retention file periodically when the retention-check timer activated.

9. The GNSD driver of claim 8 wherein the retention manager executes a retention routine when the retention-check timer is activated;

wherein write dates of directories, sub-directories, and files in the retention file are checked, wherein when the write date is before a target write date the write date is updated to a current date when data was moved;

wherein the write date is updated in the retention file.

10. The GNSD driver of claim 8 wherein the retention file only records an earliest write date of directories, sub-directories and files of the file system;

wherein the retention manager executes a retention routine when the retention-check timer activated;

wherein directories, sub-directories and files are rewritten when the write date in the retention file is before a target write date to ensure data retention;

wherein the write date is updated in the retention file.

11. A method for refreshing a flash memory comprising:

obtaining a current date;

for a current block in a list of blocks in the flash memory;

(a) reading a block status table for a write date of the current block that indicates when the current block was last written;

calculating a first time delay as a difference of the write date and the current date;

comparing the first time delay to a retention time;

when the first time delay exceeds the retention time, moving all valid pages in the current block to empty pages in a spare block in a dynamic-random-access memory (DRAM);

moving data from the spare block in DRAM to a spare block in the flash memory;

erasing the current block;

selecting another block in the list of blocks of flash memory as the current block and repeating from (a) until all blocks in the list of blocks have been processed,

whereby flash blocks are refreshed.

12. The method for refreshing the flash memory of claim 11 further comprising:

when the spare block in the DRAM is full, moving data from the spare block in DRAM to a spare block in the flash memory.

13. The method for refreshing the flash memory of claim 11 wherein the current block is a physical block having a physical-block address (PBA).

14. A retention card comprising:

an upstream interface to a host that provides power and firmware upgrade;

a controller with a retention manager firmware;

a DRAM that provides storage for the retention manager firmware; and

a protocol controller that provides a plurality of interfaces to peripheral devices that include a flash drive.

15. The retention card of claim 14 wherein the plurality of interfaces comprise external interfaces wherein the external interfaces comprise at least two of:

a Serial AT-Attachment (SATA) bus, a Peripheral Components Interconnect Express (PCIe) bus, a compact flash (CF) bus, a Universal-Serial-Bus (USB), a Non-Volatile-Memory NVMe bus, a Firewire 1394 bus, a Fibre Channel (FC) bus, and a Thunderbolt bus.

16. The retention card of claim 14 wherein the retention manager firmware for executing on the retention card comprises:

a retention-check timer that indicates when a retention-check period of time has elapsed;

a retention manager that is periodically activated by the retention-check timer, the retention manager ensuring that flash data is moved to a new flash block before a data-retention time has elapsed, wherein flash data is subject to loss when the data-retention time is exceeded, the retention manager sending commands to the flash drive to perform retention operations to write flash data.

17. The retention card of claim 16 wherein the flash drive is a Super Enhanced Endurance Device (SEED);

wherein the retention manager firmware further comprises;

a vendor command sent by the retention manager to the SEED, the vendor command causing the SEED to perform a retention operation that moves physical blocks of flash data having a write date before a target write date to ensure data retention.

18. The retention card of claim 16 wherein the flash drive is a non-Super Enhanced Endurance Device (SEED) flash drive;

wherein the retention manager creates a retention file of write dates of all directories/subdirectories and files for the file system, and stores the retention file to the flash drive;

wherein the retention manager manages the retention file periodically when the retention-check timer activated.

19. The retention card of claim 14 further comprising:

an external AC/DC power connector that provides external power;

a battery that provides power to the retention card when external power is not available;

a power management circuit to manage charging of the battery and power sources selection; and

Light-Emitting Diodes (LEDs) to display a status of retention card.

20. A retention flash drive system comprising:

a retention manager that is periodically activated when a retention-check timer has elapsed, the retention manager sending a vendor command to a Super Enhanced Endurance Device (SEED) that causes the SEED to move physical blocks of data before a data-retention limit is reached wherein data stored in flash memory is lost, the retention manager also commanding a Solid-State Drive (SSD) to move a logical block before the data-retention limit is reached;

an upper-level file filter driver, for executing on a host, for intercepting high-level host writes to a flash drive;

an encryption/decryption engine, coupled to receive high-level host writes intercepted by the upper-level file filter driver, for generating encrypted data and for decrypting encrypted data;

a compression/decompression engine, coupled to receive high-level host writes from the upper-level file filter driver, for generating compressed data and for decompressing compressed data;

wherein compressed data and encrypted data are sent to a File System Driver (FSD) executing on the host;

a lower-level file filter driver, for executing on the host, for intercepting lower-level file system host writes to a flash drive system;

a data write cache for storing host write data;

a data read cache for storing data for reading by the host;

a grouping engine for grouping data stored in the data write cache into meta-pages;

an un-grouping engine for un-grouping data in stored in meta-pages into ungrouped data for storage in the data read cache;

wherein meta-pages are sent from the grouping engine to a volume manager for transfer to a flash memory, and meta-pages stored in the flash memory are received by the un-grouping engine;

a file priority tag sorter for generating a data type for a host write received;

a task policy assignor for assigning a priority to tasks including writing of host write data by the data type, wherein priority is a function of the data type from the file priority tag sorter;

a performance adjustor for adjusting priority of tasks;

a target assignor for sorting host write data based on the data type generated by the file priority tag sorter;

a flush manager for flushing data stored in a host DRAM to a SSD DRAM and then to a flash memory of a flash drive system when power is lost;

a resume manager reloader for fetching flushed data from the flash memory of the flash drive system and then to the host DRAM when power is restored; and

a disk miniport driver for managing vendor-specific functions of the flash drive system.