Data-retention controller/driver for stand-alone or hosted card reader, solid-state-drive (SSD), or super-enhanced-endurance SSD (SEED)

• US 9,720,616 B2
• Filed: 11/09/2015
• Issued: 08/01/2017
• 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
• Primary Examiner(s): TSAI, SHENG JEN
• Application Number:
  US14/935,996
• Publication Number:
  US 20160070474A1
• Time in Patent Office: 631 Days
• Field of Search: 711103
• 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 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 flash drive that causes the flash drive 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.

2. The retention flash drive system of claim 1 further comprising:

a retention file, created by the retention manager, of write date of all directories/subdirectories and files based on a file system;

wherein the retention manager stores the retention file to the flash drive;

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

3. The retention flash drive system of claim 2 further comprising:

a retention routine executed by the retention manager when the retention-check timer is activated;

wherein retention routine checks write dates of directories, sub-directories, and files in the retention file, 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.

4. The retention flash drive system of claim 2 further comprising:

a retention routine executed by the retention manager when the retention-check timer is activated;

wherein the retention routine writes into the retention file only an earliest write date of directories, sub-directories and files of the file system;

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.

5. The retention flash drive system of claim 2 wherein the vendor command causes the flash drive to move a block at a single physical block address to a location of a new physical block address.

6. The retention flash drive system of claim 2 wherein the vendor command causes the flash drive to move all physical blocks of data without regard to write dates.

7. The retention flash drive system of claim 2 wherein the lower-level file filter driver intercepts lower-level file system host writes to the flash drive system carried on an interface in a plurality of interfaces;

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.

8. The retention flash drive system of claim 2 further comprising:

a retention routine executed by the retention manager when the retention-check timer is activated;

the retention routine comprising a method for refreshing a flash memory, the method 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.

9. The retention flash drive system of claim 8 wherein the method of the retention routine further comprises:

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.

10. The retention flash drive system of claim 8 wherein the current block is a physical block having a physical-block address (PBA).

11. The retention flash drive system of claim 2 wherein the lower-level file filter driver intercepts lower-level file system host writes to the flash drive system carried on an interface in a plurality of interfaces;

wherein the plurality of interfaces include 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.

12. The retention flash drive system of claim 2 wherein the lower-level file filter driver intercepts lower-level file system host writes to the flash drive system carried on an interface in a plurality of interfaces;

wherein the plurality of interfaces include internal interfaces, 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.