Improving storage system availability with D-GRAID

  • Authors:
  • Muthian Sivathanu;Vijayan Prabhakaran;Andrea C. Arpaci-Dusseau;Remzi H. Arpaci-Dusseau

  • Affiliations:
  • University of Wisconsin, Madison, Madison, WI;University of Wisconsin, Madison, Madison, WI;University of Wisconsin, Madison, Madison, WI;University of Wisconsin, Madison, Madison, WI

  • Venue:
  • ACM Transactions on Storage (TOS)
  • Year:
  • 2005

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Abstract

We present the design, implementation, and evaluation of D-GRAID, a gracefully degrading and quickly recovering RAID storage array. D-GRAID ensures that most files within the file system remain available even when an unexpectedly high number of faults occur. D-GRAID achieves high availability through aggressive replication of semantically critical data, and fault-isolated placement of logically related data. D-GRAID also recovers from failures quickly, restoring only live file system data to a hot spare. Both graceful degradation and live-block recovery are implemented in a prototype SCSI-based storage system underneath unmodified file systems, demonstrating that powerful “file-system like” functionality can be implemented within a “semantically smart” disk system behind a narrow block-based interface.