Real-time flash memory storage with Janus-FTL

Jongmin Lee, Ahreum Kim, Moonju Park, Jongmoo Choi, Donghee Lee, Sam H. Noh

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations


Janus-FTL, a recently proposed Flash Translation Layer (FTL) software layer for flash memory storage, has the potential to reduce the worst case write time of flash memory storage by keeping hot data in the page mapping area and cold data in the block mapping area. In this paper, we present the design of the real-time Janus-FTL that guarantees worst case garbage collection cost and write response time. In the proposed FTL, each task needs to decide whether to place its data either in the page mapping area or the block mapping area. A naive optimal placement algorithm, which minimizes the worst case write time, has O(2 N) time complexity for N tasks. We propose an algorithm reducing the time complexity from O(2 N) to O(N log N). Through experiments, we verify that the real-time Janus-FTL reduces the worst case write time and, as a result, accommodates more real-time tasks than the previous state-of-the-art realtime page mapping FTL.

Original languageEnglish
Title of host publication27th Annual ACM Symposium on Applied Computing, SAC 2012
Number of pages8
StatePublished - 2012
Event27th Annual ACM Symposium on Applied Computing, SAC 2012 - Trento, Italy
Duration: 26 Mar 201230 Mar 2012

Publication series

NameProceedings of the ACM Symposium on Applied Computing


Conference27th Annual ACM Symposium on Applied Computing, SAC 2012


  • Janus-FTL
  • page mapping FTL
  • real-time flash memory storage
  • real-time garbage collection


Dive into the research topics of 'Real-time flash memory storage with Janus-FTL'. Together they form a unique fingerprint.

Cite this