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Many storage systems rely on replication to increase the availability and durability of data on untrusted storage systems. At present, such storage systems provide no strong evidence that multiple copies of the data are actually stored. Storage servers can collude to make it look like they are storing many copies of the data, whereas in reality they only(More)
We introduce a model for <i>provable data possession</i> (PDP) that can be used for remote data checking: A client that has stored data at an untrusted server can verify that the server possesses the original data without retrieving it. The model generates probabilistic proofs of possession by sampling random sets of blocks from the server, which(More)
To reduce storage overhead, cloud file systems are transitioning from replication to erasure codes. This process has revealed new dimensions on which to evaluate the performance of different coding schemes: the amount of data used in recovery and when performing degraded reads. We present an algorithm that finds the optimal number of codeword symbols needed(More)
Blizzard is a high-performance block store that exposes cloud storage to cloud-oblivious POSIX and Win32 applications. Blizzard connects clients and servers using a network with full-bisection bandwidth, allowing clients to access any remote disk as fast as if it were local. Using a novel striping scheme, Blizzard exposes high disk parallelism to both(More)
We address the problem of minimizing the I/O needed to recover from disk failures in erasure-coded storage systems. The principal result is an algorithm that finds the optimal I/O recovery from an arbitrary number of disk failures for any XOR-based erasure code. We also describe a family of codes with high-fault tolerance and low recovery I/O, e.g. one(More)
Optimal utilization of cluster computing is partly dependent upon pre-emptive process migration. However, this migration involves a host of issues, one of them being the transfer of system-dependent resources. We focus on the overhead incurred by migrated processes using sockets. We then describe a solution that we devised and implemented to avoid this(More)
Giant cell arteritis (GCA) or Temporal arteritis (TA) is an autoimmune disease and the most common type of vasculitis in the elderly. It causes inflammation of the medium and large arteries in the upper part of the body. GCA is an under-recognized cause of  head aches in the elderly, especially when it presents itself with atypical features, resulting in(More)
Ataxia, although rare, can be a symptom of many debilitating movement disorders. Hereditary ataxias are one subset of this condition and manifest when there is a genetic abnormality involved. Ataxia oculomotor apraxia type 1 (AOA1), an autosomal recessive ataxia, results from a mutation on the aprataxin gene (APTX). We characterized a novel homozygous(More)