Green NAND device (GND) driver with DRAM data persistence for enhanced flash endurance and performance

• US 9,223,642 B2
• Filed: 06/26/2013
• Issued: 12/29/2015
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Super Talent Technology, Corporation
• Original Assignee: Super Talent Technology, Corporation
• Inventors: Yu, Frank, Ma, Abraham C., Chen, Shimon, Yan, Yi Syu
• Primary Examiner(s): CHOE, YONG J
• Application Number:
  US13/927,435
• Publication Number:
  US 20140281151A1
• Time in Patent Office: 916 Days
• US Class Current: 1/1
• 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 11/00 Error detection; Error correction; Monitoring error detection, correction or monitoring in information storage based on relative movement between record carrier and transducer G11B20/18; monitoring, i.e. supervising the progress of recording or reproducing G11B27/36; in static stores G11C29/00
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 11/2015 Redundant power supplies power supply failure G06F1/30
• CPC Class Codes: G06F 11/3058 Monitoring arrangements for monitoring environmental properties or parameters of the computing system or of the computing system component, e.g. monitoring of power, currents, temperature, humidity, position, vibrations thermal management in cooling arrangements of a computing system G06F1/206
• CPC Class Codes: G06F 11/3062 where the monitored property is the power consumption power management in a computing system G06F1/3203
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0632 by initialisation or re-initialisation of storage systems
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G06F 9/4418 Suspend and resume; Hibernate and awake
• CPC Class Codes: G11C 29/08 Functional testing, e.g. testing during refresh, power-on self testing [POST] or distributed testing
• CPC Class Codes: G11C 29/52 Protection of memory contents; Detection of errors in memory contents

Abstract

A Green NAND Device (GND) driver application queries AC line and battery status and then stores an image of processor states and caches and a resume routine to DRAM when power failure occurs. A DRAM image is then stored to flash memory for a persistent mode when battery power is available. The image in DRAM may be a partial image that includes entries, flushed caches, processor contexts, ramdisks, write caches, and a resume context. Endurance of flash memory is increased by a Super Enhanced Endurance Device (SEED) SSD. In a power down mode, the GND driver limits DRAM use and only caches in DRAM data that can be deleted on power down. Host accesses to flash are intercepted by the GND driver and categorized by data type. Paging files and temporary files cached in DRAM are optionally written to flash.

Claims

1. A Green NAND Device (GND) driver with a persistent mode comprising:

a flash memory that retains stored data when power is lost;

a persistent processor image generator that copies data from a host processor state and from a processor cache memory to a volatile memory when a persistent mode power down routine is activated to generate a host processor image;

a persistent resume image stored in the volatile memory when the persistent mode power down routine is activated;

a persistent image generator that copies data from a host volatile memory to the flash memory when the persistent mode power down routine is activated to generate a persistent restore image,

wherein persistent mode is activated and executed when sufficient battery power is available;

a restore image loader that reads the persistent restore image from the flash memory to the host volatile memory when the persistent mode routine was activated at a prior power down, and executes the persistent resume image from the volatile memory to restore the host processor image.

2. The GND driver of claim 1 further comprising:

a persistent mode power/battery monitor that reads a power status line from a backup power supply and reads a battery status for a battery when the power loss is detected; and

a power down routine activated when the battery status indicates power below a threshold and power loss is indicated.

3. The GND driver of claim 1 further comprising:

a persistent mode write cache for storing host write data in a Dynamic Random Access Memory (DRAM).

4. The GND driver of claim 1 further comprising:

a persistent mode ramdisk for storing data in a Dynamic Random Access Memory (DRAM).

5. The GND driver of claim 1 further comprising:

a user interface for receiving a user selection, the power down routine being enabled and the persistent mode routine being disabled when the user selection disables persistent mode.

6. The GND driver of claim 1 further comprising:

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

7. The GND driver of claim 1 further comprising:

a persistent mode having a set of policies to trigger a write of the dirty data from caches in the volatile memory to the flash memory;

wherein the set of policies comprise a threshold level dirty data in a cache, a period of time, a special data type assigned by the user, or a full cache.

8. The GND driver of claim 1 further comprising:

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

a lower-level file filter driver, for executing on the host, for intercepting lower-level file system host writes to the flash drive and sending the lower-level file system host writes to the data split manager for sorting as the host write data.

9. The GND driver of claim 1 further comprising:

an encryption engine, coupled to receive intercepted high-level host writes, for generating encrypted data.

10. The GND driver of claim 1 further comprising:

a compression engine, coupled to receive intercepted high-level host writes, for generating compressed data and compressed mapping table.

11. The GND driver of claim 1 further comprising:

a de-duplication engine, coupled to receive intercepted high-level host writes, for generating a de-duplication mapping table.

12. The GND driver of claim 1 further comprising:

a transaction manager for logging events indicating start and completion of data writes to the flash memory; and

a recovery manager for reading events logged by the transaction manager to undo or redo writes to the flash memory after power resumes.

13. The GND driver of claim 1 further comprising:

a configuration settings manager for changing settings to improve flash endurance and performance, the settings comprising at least one of drive indexing, search indexing, page file size, system restore, hibernation, write caching, prefetching, superfetching, recycle bin size, logging, reliability monitor, and ramdisk.

14. The GND driver of claim 1 wherein the persistent restore image further comprises:

an Inter-Processing DRAM (IPDRAM) controlled by the host processor that maintains a list of starting locations of volatile memory and lengths for different data types; and

a flag to indicate that a particular data type in the volatile memory needs to be included into the persistent restore image.

15. The GND driver of claim 1 further comprising:

a power/battery monitor that reads a power status line from a backup power supply and activates the power down routine when the power status line indicates a power loss.

16. The GND driver of claim 1 further comprising:

a file type identifier for generating a data type for a host write received by the GND driver;

a data split manager for sorting host write data based on the data type generated by the file type identifier;

a data write cache for storing host write data having a user data type;

a meta-data cache for storing host write data having a meta-data data type;

a paging cache for storing host write data having a paging file data type; and

a temp cache for storing host write data having a temp data type.

17. The GND driver of claim 1 further comprising:

a user selected shut down monitor that monitor a type of shut down selected by the user;

a switch user selection routine that suspends all current user sessions and flushes caches and buffers from the volatile memory to a Solid-State Drive (SSD);

a log off selection routine that suspends all user sessions and flushes caches and buffers from the volatile memory to the SSD;

a lock selection routine that displays a screen for a password entry and waits for the user to enter a password to resume;

a restart selection routine that shuts down all applications except critical system services and then reboots;

a sleep selection routine that puts the host in a low-power state, but not in a turn-off state;

a hibernate selection routine that suspends all applications and suspend all services and device except the SSD, wherein a hibernate image is written to the SSD, and then suspends the SSD; and

a shutdown selection routine that suspends all sessions, applications, and devices.

18. The GND driver of claim 1 further comprising:

a persistent mode ramdisk for storing data in a Dynamic Random Access Memory (DRAM).