Tiered Storage Using SCM and NVRAM for Data Access
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Solution Overview
Problem
Data Storage Devices (DSDs) face limitations in storage capacity and cost when using Storage Class Memory (SCM), which is faster and more power-efficient than conventional storage media, due to its higher cost, necessitating efficient data management strategies to optimize SCM usage.
Innovation Solution
Implementing a tiered storage system that selectively uses SCM for frequently accessed, high-priority, or small data, while utilizing Non-Volatile Random Access Memory (NVRAM) and disk storage for larger data sets, with a write table and mapping systems to determine optimal storage locations based on access frequency, priority, and size, and employing caching and migration processes to maximize SCM's benefits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If Storage Class Memory (SCM) is used for data storage, then data access speed and power efficiency are improved, but storage cost increases and storage capacity is limited
Solution Approach 1:
The storage system is segmented into multiple tiers: SCM tier for frequently accessed data, NVRAM tier for less frequently accessed data, and disk tier for archival data. This segmentation allows each storage medium to be used for its optimal purpose, maximizing speed for hot data while preserving capacity for cold data.
Solution Approach 2:
Different storage media are assigned to different data characteristics: SCM provides high-speed local storage for critical data, NVRAM provides intermediate storage, and disk provides bulk storage. Each layer has optimized quality characteristics matching the data it stores.
2Use of energy by moving object
If Storage Class Memory (SCM) is used for data storage, then power consumption is reduced, but storage cost increases
Solution Approach 1:
Instead of using SCM for all storage needs, the system applies SCM partially only to the extent necessary for high-performance requirements. The majority of storage capacity uses cost-effective NVRAM and disk media, while SCM provides excessive speed for the specific subset of frequently accessed data.
3Productivity
If tiered storage with multiple media types is implemented, then storage efficiency is improved, but system complexity increases
Solution Approach 1:
A controller acts as an intermediary between the host system and the tiered storage media. The controller manages data placement, migration, and retrieval across SCM, NVRAM, and disk tiers, abstracting the complexity from the host while optimizing storage efficiency.
Solution Approach 2:
The system implements feedback mechanisms through write tables and mapping systems that track data access patterns. This feedback enables automatic data migration decisions, with frequently accessed data being moved to faster media and less frequently accessed data being moved to slower, cheaper media.
Data Source
AI summary
A Data Storage Device (DSD) includes a first memory for storing data and a Storage Class Memory (SCM) for storing data. The SCM has at least one characteristic of being faster than the first memory in storing data, using less power to store data than the first memory, and providing a greater usable life than the first memory for repeatedly storing data in a same memory location. At least a portion of the SCM is allocated or reserved for use by a host, and logical addresses assigned to the SCM are mapped to device addresses of the first memory identifying locations for storing data in the first memory. The host is provided with an indication of the logical addresses assigned to the SCM to allow the host to retrieve data from and store data in the DSD or to directly access data using the logical addresses assigned to the SCM.