Project almanac: A time-traveling solid-state drive

Xiaohao Wang, Yifan Yuan, You Zhou, Chance C. Coats, Jian Huang

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Preserving the history of storage states is critical to ensuring system reliability and security. It facilitates system functions such as debugging, data recovery, and forensics. Existing software-based approaches like data journaling, logging, and backups not only introduce performance and storage cost, but also are vulnerable to malware attacks, as adversaries can obtain kernel privileges to terminate or destroy them. In this paper, we present Project Almanac, which includes (1) a time-travel solid-state drive (SSD) named TimeSSD that retains a history of storage states in hardware for a window of time, and (2) a toolkit named TimeKits that provides storage-state query and rollback functions. TimeSSD tracks the history of storage states in the hardware device, without relying on explicit backups, by exploiting the property that the flash retains old copies of data when they are updated or deleted. We implement TimeSSD with a programmable SSD and develop TimeKits for several typical system applications. Experiments, with a variety of real-world case studies, demonstrate that TimeSSD can retain all the storage states for eight weeks, with negligible performance overhead, while providing the device-level time-travel property.

Original languageEnglish (US)
Title of host publicationProceedings of the 14th EuroSys Conference 2019
PublisherAssociation for Computing Machinery, Inc
ISBN (Electronic)9781450362818
StatePublished - Mar 25 2019
Event14th European Conference on Computer Systems, EuroSys 2019 - Dresden, Germany
Duration: Mar 25 2019Mar 28 2019

Publication series

NameProceedings of the 14th EuroSys Conference 2019


Conference14th European Conference on Computer Systems, EuroSys 2019


  • Firmware-isolated logging
  • Solid-state drive
  • Time travel

ASJC Scopus subject areas

  • Hardware and Architecture
  • Electrical and Electronic Engineering


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