Enterprise data storage system using multi-level cell flash memory

• US 8,239,617 B1
• Filed: 02/12/2010
• Issued: 08/07/2012
• Est. Priority Date: 02/12/2010
• Status: Active Grant

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Linnell, Thomas E.
• Primary Examiner(s): CHOE, YONG J
• Application Number:
  US12/705,471
• Time in Patent Office: 907 Days
• Field of Search: 711/103, 711/111, 711/E12.008
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0804 with main memory updating G06F12/0806 takes precedence
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2206/1012 Load balancing
• CPC Class Codes: G06F 2212/214 Solid state disk
• CPC Class Codes: G06F 2212/7204 Capacity control, e.g. partitioning, end-of-life degradation
• 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 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays
• CPC Class Codes: G11C 2211/5641 Multilevel memory having cells with different number of storage levels

Abstract

A system including an enterprise data storage system having a plurality of multi-level cell (MLC) flash devices configured as data storage drives. The enterprise data storage system is operated in such a way and the configuration of the MLC flash devices is such that the enterprise data storage system is able to maintain a performance level comparable to that of an enterprise data storage system utilizing single-level cell (SLC) flash devices.

Claims

1. A data storage system comprising:

a host;

a controller; and

a data storage drive comprising;

a plurality of flash memory elements;

a first memory portion including a first number of the flash memory elements; and

a second memory portion including a second number of the flash memory elements, the second memory portion being exclusive of the first memory portion;

wherein the first memory portion and the second memory portion combine to represent an actual capacity of the data storage drive and the first memory portion represents an advertised capacity of the data storage drive, the advertised capacity of the first memory portion being presented to the host by the controller as a total capacity of the data storage drive; and

wherein data writes from the host to the data storage drive are written to a capacity of flash memory elements corresponding to the advertised capacity, but wherein data writes are spread over the actual capacity of the data storage drive.

2. The system of claim 1 wherein data storage drive is a flash drive and the flash memory elements comprise MLC (multi-level cell) flash memory chips.

3. The system of claim 1 wherein data storage drive is a virtual disk and the flash memory elements comprise flash drive chunks, each including a number of MLC flash memory chips.

4. The system of claim 1 wherein data storage drive is a RAID (Redundant Array of Inexpensive Disks)-configured drive array and the flash memory elements comprise flash drive chunks, each including a number of MLC flash memory chips.

5. The system of claim 1 wherein the controller further includes a load balancer device configured to monitor a cumulative number of data writes from the host to each of the flash memory elements and to direct data writes to flash memory elements having fewer data writes compared to other flash memory elements in the system.

6. The system of claim 1 further including a cache memory device configured to temporarily store data writes from the host to the data storage drive, wherein a data write is temporarily stored in the cache for a period of time and, if the data write is rewritten during the period of time, it is rewritten in the cache memory device.

7. A method of increasing the durability of a data storage system including a plurality of MLC (multi-level cell) flash drives comprising:

overprovisioning a data storage drive comprising a plurality of MLC flash memory devices by forming a first memory portion including a first number of the MLC flash memory devices and a second memory portion including a second number of the MLC flash memory devices, the second memory portion being exclusive of the first memory portion;

wherein the first memory portion and the second memory portion combine to represent an actual capacity of the data storage drive and the first memory portion represents an advertised capacity of the data storage drive;

presenting the advertised capacity of the first memory portion being to a host by a controller as a total capacity of the data storage drive;

writing an amount of data writes from the host to flash memory devices of the data storage drive corresponding to the advertised capacity; and

spreading the data writes over the flash memory devices of the data storage drive corresponding to the actual capacity of the data storage drive.

8. The method of claim 7 further comprising monitoring a cumulative number of data writes from the host to each of the flash memory devices and to directing data writes to flash memory devices having fewer data writes compared to other flash memory devices in the system.

9. The method of claim 7 further comprising temporarily storing, in cache, data writes from the host to the data storage drive, wherein a data write is temporarily stored in the cache for a period of time and, if the data write is rewritten during the period of time, it is rewritten in the cache memory device;

and writing the data write to the data storage drive upon an expiration of the period of time.

10. The method of claim 7 further comprising monitoring an age of data being written to the data storage drive and writing newer data to flash memory devices of the data storage drive and writing older data to magnetic drives of the data storage drive.

11. The method of claim 7 further comprising monitoring a demand associated with data being written to the data storage drive and writing high-demand data to flash memory devices of the data storage drive and writing low-demand data to magnetic drives of the data storage drive.