Persistent Memory Write Acknowledgment for Low-Latency Chunk Storage
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Solution Overview
Problem
Existing data storage systems face challenges in efficiently handling small input/output operations (IOs) due to high latency and write amplification, particularly when using solid state drives (SSDs) and hard disk drives (HDDs), and require costly investments for improved performance and resilience.
Innovation Solution
Implementing a data storage system with persistent memory (PMEM) that writes data concurrently to both PMEM and chunk storage, acknowledging successful storage after completing writes to PMEM but before completing writes to chunk storage, thereby leveraging PMEM's faster write speeds to reduce latency and minimize SSD wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data is written to traditional storage systems (SSDs/HDDs), then data persistence is achieved, but high latency and write amplification occur
Solution Approach 1:
The system pre-writes data to persistent memory before the traditional storage operation is complete. By performing the write operation to PMEM first and acknowledging the client before the traditional storage (SSD/HDD) finishes writing, the system eliminates the latency associated with waiting for traditional storage to complete, while still ensuring data persistence through the dual-write mechanism.
2Reliability
If persistent memory is used for immediate write acknowledgment, then latency is reduced, but data durability may be compromised
Solution Approach 1:
The system merges the write operations to both persistent memory and traditional storage into a single coordinated process. By using synchronous dual-write where both PMEM and traditional storage must complete successfully before the operation finishes, the system achieves both high performance (from PMEM) and data durability (from the coordinated completion mechanism), resolving the contradiction between speed and reliability.
3Productivity
If concurrent writes to PMEM and chunk storage are implemented, then write amplification is reduced, but system complexity increases
Solution Approach 1:
The system introduces an intermediary coordination mechanism that manages the concurrent writes to PMEM and traditional storage. This intermediary layer handles the synchronization, error handling, and completion tracking, allowing the system to achieve write efficiency through concurrent operations while containing the added complexity through a dedicated coordination subsystem rather than scattered complexity throughout the system.
Data Source
AI summary
A system can maintain a data storage system, wherein the data storage system comprises persistent memory and chunk storage, wherein the persistent memory is more performant than the chunk storage, wherein the chunk storage stores data in chunks of a fixed-size, and wherein respective chunks of the chunks correspond to respective parity values. The system can, based on receiving a request associated with a storage account to write data to the data storage system, write the data to the persistent memory concurrently with writing the data to the chunk storage. The system can, after completing writing the data to the persistent memory and before completing writing the data to the chunk storage, send an indication, to the storage client, that the data has been successfully stored in the data storage system.