Prioritized access for media with heterogeneous access rates

• US 9,003,101 B1
• Filed: 06/29/2011
• Issued: 04/07/2015
• Est. Priority Date: 06/29/2011
• Status: Active Grant

• Current Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Fallone, Robert M., Boyle, William B.
• Primary Examiner(s): Ruiz, Aracelis
• Application Number:
  US13/172,737
• Time in Patent Office: 1,378 Days
• Field of Search: 711/102, 711/103, 711/170
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0238 Memory management in non-volatile memory, e.g. resistive RAM or ferroelectric memory
• CPC Class Codes: G06F 12/0802 Addressing of a memory level in which the access to the desired data or data block requires associative addressing means, e.g. caches
• CPC Class Codes: G06F 2212/1016 Performance improvement
• CPC Class Codes: G06F 2212/214 Solid state disk
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• 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: G11C 2211/5641 Multilevel memory having cells with different number of storage levels

Abstract

A non-volatile storage subsystem is described which identifies performance-sensitive commands and heterogeneous performance characteristics of portions of a non-volatile storage media, and matches the performance sensitivity of the commands with an available physical write address corresponding to performance characteristics appropriate for the performance sensitivity of the command. A command can be considered performance sensitive if it originates from a host or a preferred host among a plurality of hosts, or if the command designates a frequently accessed logical address. Performance characteristics of the storage device can be determined by physical architectures of the storage media such as the distance from the axial center of a disk media, or the architecture technology of a solid-state array. Performance characteristics can also be determined dynamically and heterogeneous performance can be encouraged by internal maintenance policies of the subsystem.

Claims

1. A non-volatile storage subsystem, comprising:

non-volatile storage media comprising a solid-state storage array, the non-volatile storage media including a higher write performance portion and a lower write performance portion; and

a controller configured to;

perform wear leveling operations on the solid-state storage array;

designate at least one portion of the solid-state storage array as a portion with reduced wear compared to other portions of the solid-state storage array and maintain the designated at least one portion of the solid-state storage array as the portion with reduced wear compared to the other portions of the solid-state storage array, the higher write performance portion comprising the designated at least one portion of the solid-state storage array;

maintain a list of available storage locations for the non-volatile storage media;

receive a write command comprising a logical address and write data;

determine a performance sensitivity associated with the write command, the write command having a higher performance sensitivity when it is received from a host system and having a lower performance sensitivity when it is received from a maintenance process internal to the non-volatile storage subsystem; and

in response to determining that the write command has the higher performance sensitivity, execute the write command in a storage location of the designated at least one portion of the solid-state storage array chosen from the list of available storage locations.

2. The non-volatile storage subsystem of claim 1, wherein the non-volatile storage media further comprises a hard disk device, the higher write performance portion comprising a first portion of the hard disk device and the lower write performance portion comprising a second portion of the hard disk device, and the controller is further configured to:

receive another write command,

in response to determining that the another write command has the higher performance sensitivity, execute the another write command in the first portion of the hard disk device, and

in response to determining that the another write command has the lower performance sensitivity, execute the another write command in the second portion of the hard disk device.

3. The non-volatile storage subsystem of claim 2, wherein the hard disk device comprises a hard disk platter, the first portion of the hard disk device comprising an outer diameter region of the hard disk platter and the second portion of the hard disk device comprising an inner diameter region of the hard disk platter.

4. The non-volatile storage subsystem of claim 2, wherein the hard disk device comprises a plurality of hard disk platters, and the first and second portions of the hard disk device are defined by different performance characteristics of different surfaces of the plurality of hard disk platters.

5. The non-volatile storage subsystem of claim 2, wherein the hard disk device comprises a hard disk platter, and the first and second portions of the hard disk device are assigned based at least in part by a current rotational position of a portion of the hard disk platter relative to a write head of the hard disk device.

6. The non-volatile storage subsystem of claim 1, wherein the controller is further configured to store, in the designated at least one portion of the solid-state storage array, data addressed by frequently written logical addresses.

7. The non-volatile storage subsystem of claim 1, wherein the non-volatile storage media comprises a plurality of solid-state storage arrays including the solid-state storage array.

8. The non-volatile storage subsystem of claim 7, wherein the higher write performance portion includes a Single-Level Cell (SLC) storage array of the plurality of solid-state storage arrays and the lower write performance portion includes a Multi-Level Cell (MLC) storage array of the plurality of solid-state storage arrays.

9. The non-volatile storage subsystem of claim 1, wherein the performance sensitivity of the write command is based at least partly on whether the logical address is a frequently accessed logical address.

10. The non-volatile storage subsystem of claim 1, wherein the determined performance sensitivity corresponds to one performance sensitivity value of more than two performance sensitivity values.

11. A method for assigning a physical address location to a write command in a non-volatile storage subsystem, comprising:

performing wear leveling operations on a solid-state storage array;

designating at least one portion of the solid-state storage array as a portion with reduced wear compared to other portions of the solid-state storage array and maintaining the designated at least one portion of the solid-state storage array as the portion with reduced wear compared to the other portions of the solid-state storage array;

maintaining a list of available physical address locations of non-volatile storage media including the solid-state storage array, each available physical address location associated with a performance characteristic, the list being organized by the performance characteristic of the available physical address locations;

determining a performance sensitivity associated with the write command;

assigning the physical address location from the available physical address locations to the write command based at least in part on the determined performance sensitivity associated with the write command and the performance characteristic of the physical address location;

wherein when the write command is received from a host, the write command is deemed to have a high performance sensitivity and is assigned an available physical address from the list corresponding to the designated at least one portion of the solid-state storage array,

wherein when the write command is received from a management process internal to the non-volatile storage subsystem, the write command is deemed have a low performance sensitivity and is assigned an available physical address from the list corresponding to a portion of the solid-state storage array other than the designated at least one portion of the solid-state storage array,

wherein the method is performed by a controller in the non-volatile storage subsystem.

12. The method of claim 11, wherein the determination of the performance sensitivity of the write command is based partly on whether the write command designates a frequently accessed logical address.

13. A non-volatile storage system comprising:

non-volatile storage media comprising a solid-state storage array, the non-volatile storage media including a higher write performance portion and a lower write performance portion; and

a controller configured to;

perform wear leveling operations on the solid-state storage array;

designate at least one portion of the solid-state storage array as a portion with reduced wear compared to other portions of the solid-state storage array and maintain the designated at least one portion of the solid-state storage array as the portion with reduced wear compared to the other portions of the solid-state storage array, the higher write performance portion comprising the designated at least one portion of the solid-state storage array;

receive a write command from a host;

receive a write command from an internal component;

maintain a list of available write locations for the non-volatile storage media;

assign a write location to the write command from the host chosen from the list of available write locations based at least in part on a preference for assigning available write locations from the higher write performance portion of the non-volatile storage media to write commands from the host, the chosen write location assigned to the write command from the host being a memory location of the designated at least one portion of the solid-state storage array; and

assign a write location to the write command from the internal component chosen from the list of available write locations based at least in part on a preference for assigning available write locations from the lower write performance portion of the non-volatile storage media to write commands from the internal component.

14. The non-volatile storage system of claim 13, wherein the non-volatile storage media further comprises a hard disk platter, and the higher write performance portion further comprises an exterior portion of the hard disk platter and the lower write performance portion further comprises an interior portion of the hard disk platter.

15. The non-volatile storage system of claim 13, wherein the non-volatile storage media further comprises a plurality of hard disk platters, and the higher write performance portion further comprises a first of the plurality of hard disk platters and the lower write performance portion further comprises a second of the plurality of hard disk platters.

16. The non-volatile storage system of claim 13, wherein the non-volatile storage media further comprises at least one hard disk platter, and the higher write performance portion further comprises a first surface on the at least one hard disk platter and the lower write performance portion further comprises a second surface on the at least one hard disk platter.

17. A non-volatile storage subsystem, comprising:

non-volatile storage media comprising a solid-state storage array, the non-volatile storage media including a higher write performance portion and a lower write performance portion; and

a controller configured to;

perform wear leveling operations on the solid-state storage array;

designate at least one portion of the solid-state storage array as a portion with reduced wear compared to other portions of the solid-state storage array and maintain the designated at least one portion of the solid-state storage array as the portion with reduced wear compared to the other portions of the solid-state storage array, the higher write performance portion comprising the designated at least one portion of the solid-state storage array;

maintain a list of available write locations for the non-volatile storage media;

receive a write command comprising a logical address and write data;

determine a performance sensitivity associated with the write command in part based on a run-time characteristic of the non-volatile storage subsystem and whether the write command is received from a host system or a maintenance process internal to the non-volatile storage subsystem; and

select a write location either in the higher write performance portion or the lower write performance portion of the storage media chosen from the list of available write locations based at least in part on the determined performance sensitivity associated with the write command.

18. The non-volatile storage subsystem of claim 17, wherein the run-time characteristic comprises a remaining storage capacity of the non-volatile storage media.

19. The non-volatile storage subsystem of claim 18, wherein the non-volatile storage media comprises a plurality of solid-state storage arrays including the solid-state storage array, and wherein the higher write performance portion includes a Single-Level Cell (SLC) storage array of the plurality of solid-state storage arrays and the lower write performance portion includes a Multi-Level Cell (MLC) storage array of the plurality of solid-state storage arrays.