Multi-Grained Block Management to Enhance the Space Utilization of File Systems on PCM Storages

Tseng Yi Chen, Yuan Hao Chang, Ming Chang Yang, Yun Jhu Chen, Hsin Wen Wei, Wei Kuan Shih

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Phase-change memory (PCM) is a promising candidate as a storage medium to resolve the performance gap between main memory and storage in battery-powered mobile computing systems. However, it is more expensive than flash memory, and thus introduces a more serious storage capacity issue for low-cost solutions. This issue is further exacerbated by the fact that existing file systems are usually designed to trade space utilization for performance over block-oriented storage devices. In this work, we propose a multi-grained block management strategy to improve the space utilization of file systems over PCM-based storage systems. By utilizing the byte-addressability and fast read/write feature of PCM, a methodology is proposed to dynamically allocate multiple sizes of blocks to fit the size of each file, so as to resolve the space fragmentation issue with minimized space and management overheads. The space utilization of file systems is analyzed with consideration of block sizes. A series of experiments was conducted to evaluate the efficacy of the proposed strategy, and the results show that the proposed strategy can significantly improve the space utilization of file systems.

Original languageEnglish
Article number7155504
Pages (from-to)1831-1845
Number of pages15
JournalIEEE Transactions on Computers
Issue number6
StatePublished - 1 Jun 2016


  • Phase-change memory
  • byte-addressability
  • file systems
  • space utilization


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