Storage Controller Over Provisioning via RAID Spare Area

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Solution Overview

Problem

Flash memory devices do not support overwrite operations, leading to decreased access speed and unusable storage capacity due to the need for erase operations before writing, which also limits the storage capacity available to host devices.

Innovation Solution

A storage device with a controller that divides its nonvolatile memory space into user, meta, and over provision areas, using RAID spare information to select a RAID spare area as an over provision area, thereby improving access speed and reducing unusable storage capacity by allowing write operations without erasing existing data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a partial storage area is used as an over provision area to improve access speed, then write operations can be performed without erasing existing data, but the storage capacity available to the host device decreases

Engineering Contradiction:

Improveaccess speedVSAvoidstorage capacity

Core Design Contradiction:

SpeedVSQuantity of substance

Solution Approach 1:

The storage space is segmented into user area, meta area, and over provision area. The over provision area is further divided into first over provision area and second over provision area based on RAID spare information. This segmentation allows the system to allocate specific portions for performance optimization while preserving the majority of storage capacity for host device usage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts the allocation of storage areas based on RAID spare information parameters. By receiving RAID spare information from the host device and selecting appropriate areas, the system optimizes the balance between access speed and storage capacity without requiring a fixed, predetermined allocation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If flash memory device performs erase operation before write operation, then data can be written in specific area, but access speed decreases due to additional operation steps

Engineering Contradiction:

Improvedata integrityVSAvoidaccess speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The over provision area is prepared in advance by allocating it separately from the user area. This preliminary action enables the system to perform write operations directly in the over provision area without requiring erase operations, as the area is pre-configured for write-only or write-optimized operations, thus improving access speed while maintaining data integrity in the user area.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The over provision area is extracted from the user area and managed separately. This extraction allows write operations to be performed independently in the over provision area without affecting the user area, eliminating the need for erase-before-write operations and thereby improving access speed while preserving data integrity in the main storage area.

Inventive Principle:

Principle #2Taking out (Extraction)

3Quantity of substance

If RAID spare area is used as over provision area, then storage efficiency improves by reducing unusable capacity, but data reliability for RAID operations may be affected

Engineering Contradiction:

Improveusable storage capacityVSAvoiddata reliability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

Different portions of the storage space are assigned different qualities and functions. The first over provision area maintains higher reliability for critical operations, while the second over provision area (derived from RAID spare area) is optimized for performance. This local quality differentiation allows the system to utilize RAID spare area for improving storage efficiency while preserving data reliability in critical areas.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The over provision area serves multiple functions: it acts as a buffer for write operations to improve access speed, provides additional storage capacity by utilizing RAID spare area, and maintains data reliability through separate management from the user area. This multi-functionality resolves the contradiction between storage efficiency and data reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11079943B2Storage devices including improved over provision management and operating methods of such storage devices

Publication Date: 2021.08.03 SAMSUNG ELECTRONICS CO LTD

AI summary

A storage device includes a nonvolatile memory device including a storage space, and a controller that is configured to divide and manage the storage space of the nonvolatile memory device into a user area and a meta area and to provide access to the user area to a host device. Responsive to receiving Redundant Array of Inexpensive Disks (RAID) spare information from the host device, the controller is further configure to select a RAID spare area from the user area based on the RAID spare information and to use at least a portion of the RAID spare area as an over provision area.