WrJFS: A Write-Reduction Journaling File System for Byte-addressable NVRAM

Tseng Yi Chen, Yuan Hao Chang, Shuo Han Chen, Chih Ching Kuo, Ming Chang Yang, Hsin Wen Wei, Wei Kuan Shih

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Non-volatile random-access memory (NVRAM) becomes a mainstream storage device in embedded systems due to its favorable features, such as small size, low power consumption, and short read/write latency. Unlike dynamic random access memory (DRAM), NVRAM has asymmetric performance and energy consumption on read/write operations. Generally, on NVRAM, a write operation consumes more energy and time than a read operation. Unfortunately, current mobile/embedded file systems, such as EXT2/3 and EXT4, are very unfriendly for NVRAM devices. The reason is that current mobile/embedded file systems employ a journaling mechanism for increasing its data reliability. Although a journaling mechanism raises the safety of data in a file system, it also repeatedly writes data to a data storage while data is committed and checkpointed. Though several related works have been proposed to reduce the amount of write traffic to NVRAM, they still cannot effectively minimize the write amplification of a journaling mechanism. Such observations motivate us to design a two-phase write reduction journaling file system called wrJFS. In the first phase, wrJFS classified data into two categories: Metadata and user data. As the size of metadata is usually very small (few bytes), byte-enabled journaling strategy will handle metadata during commit and checkpoint stages. In contrast, the size of user data is very large relative to metadata; thus, user data will be processed in the second phase. In the second phase, user data will be compressed by hardware encoder to reduce the write size and managed compressed-enabled journaling strategy to avoid the write amplification on NVRAM. Moreover, we analyze the overhead of wrJFS and show that the overhead is negligible. According to the experimental results, the proposed wrJFS outperforms other journaling file systems even though the experiments include the overhead of data compression.

Original languageEnglish
Article number8260880
Pages (from-to)1023-1038
Number of pages16
JournalIEEE Transactions on Computers
Volume67
Issue number7
DOIs
StatePublished - 1 Jul 2018

Keywords

  • Write reduction
  • data compression
  • journaling file system
  • non-volatile memory

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