Paper 2010/214

How to Tell if Your Cloud Files Are Vulnerable to Drive Crashes

Kevin D. Bowers, Marten van Dijk, Ari Juels, Alina Oprea, and Ronald L. Rivest


This paper presents a new challenge---verifying that a remote server is storing a file in a fault-tolerant manner, i.e., such that it can survive hard-drive failures. We describe an approach called the Remote Assessment of Fault Tolerance (RAFT). The key technique in a RAFT is to measure the time taken for a server to respond to a read request for a collection of file blocks. The larger the number of hard drives across which a file is distributed, the faster the read-request response. Erasure codes also play an important role in our solution. We describe a theoretical framework for RAFTs and show experimentally that RAFTs can work in practice.

Note: Updated to include testing performed against the Mozy online backup service.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Unknown where it was published
applicationserasure codesstorage
Contact author(s)
ajuels @ rsa com
2011-05-13: last of 6 revisions
2010-04-19: received
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Creative Commons Attribution


      author = {Kevin D.  Bowers and Marten van Dijk and Ari Juels and Alina Oprea and Ronald L.  Rivest},
      title = {How to Tell if Your Cloud Files Are Vulnerable to Drive Crashes},
      howpublished = {Cryptology ePrint Archive, Paper 2010/214},
      year = {2010},
      note = {\url{}},
      url = {}
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