Daniel Ellard

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We present an analysis of a pair of NFS traces of contemporary email and research workloads. We show that although the research workload resembles previouslystudied workloads, the email workload is quite different. We also perform several new analyses that demonstrate the periodic nature of file system activity, the effect of out-of-order NFS calls, and the(More)
We present decoy routing, a mechanism capable of circumventing common network filtering strategies. Unlike other circumvention techniques, decoy routing does not require a client to connect to a specific IP address (which is easily blocked) in order to provide circumvention. We show that if it is possible for a client to connect to any unblocked(More)
This paper describes the design, implementation, and evaluation of TBBT, the first comprehensive NFS trace replay tool. Given an NFS trace, TBBT automatically detects and repairs missing operations in the trace, derives a file system image required to successfully replay the trace, ages the file system image appropriately, initializes the file server under(More)
To tune and manage themselves, file and storage systems must understand key properties (e.g., access pattern, lifetime, size) of their various files. This paper describes how systems can automatically learn to classify the properties of files (e.g., read-only access pattern, short-lived, small in size) and predict the properties of new files, as they are(More)
We describe two modifications to the FreeBSD 4.6 NFS server to increase read throughput by improving the read-ahead heuristic to deal with reordered requests and stride access patterns. We show that for some stride access patterns, our new heuristics improve end-to-end NFS throughput by nearly a factor of two. We also show that benchmarking and(More)
Virtualization is a well-known method of abstracting physical resources and of separating the manipulation and use of logical resources from their underlying implementation. We have used this technique to virtualize file volumes in the WAFL R © file system, adding a level of indirection between client-visible volumes and the underlying physical storage. The(More)
Decoy routing is a powerful circumvention mechanism intended to provide secure communications that cannot be monitored, detected, or disrupted by a third party who controls the user's network infrastructure. Current decoy routing protocols have weaknesses, however: they either make the unrealistic assumption that routes through the network are symmetric(More)
Passive NFS traces provide an easy and unobtrusive way to measure, analyze, and gain an understanding of an NFS workload. Historically, such traces have been used primarily by file system researchers in an attempt to understand, categorize, and generalize file system workloads. However, because such traces provide a wealth of detailed information about how(More)
Ant-32 is a new processor architecture designed specifically to address the pedagogical needs of teaching many subjects, including assembly language programming, machine architecture, compilers, operating systems, and VLSI design. This paper discusses our motivation for creating Ant-32 and the philosophy we used to guide our design decisions and gives a(More)