Predicting File System Actions from Prior Events

We have adapted a multi-order context modeling technique used in the data compression method Prediction by Partial Match (PPM) to track sequences of file access events. From this model, we are able to determine file system accesses that have a high probability of occurring as the next event. By prefetching the data for these events, we have transformed an LRU cache into a predictive cache that in our simulations averages 15% more cache hits than LRU. In fact, on average our fourmegabyte predictive cache has a higher cache hit rate than a 90 megabyte LRU cache. 1 Introduction With the rapid increase of processor speeds, file system latency is a critical issue in computer system performance [14]. Standard Least Recently Used (LRU) based caching techniques offer some assistance, but by ignoring any relationships that exist between file system events, they fail to make full use of the available information. We will show that many of the events in a file system are closely related. For exa..

Resilient Memory-Resident Data Objects

: Data replication has been widely used to build resilient data objects. These objects normally consist of several replicas stored in stable storage and a replication control protocol managing these replicas. Replicated data objects incur a significant penalty resulting from the increased number of disk accesses. We investigate the feasibility of replicated data objects consisting of several memory-resident replicas and one append-only log maintained on disk. We analyze, under standard Markovian hypotheses, the availability of these data objects when combined with three of the most popular replication control protocols: available copy (AC), majority consensus voting (MCV) and dynamic-linear voting (DLV). We show that replicated objects consisting of n memory-resident replicas and a disk-resident log have almost the same availability as replicated objects having n disk-resident replicas. Keywords: file replication, replicated databases, memory-resident databases, majority consensus vo..

Modeling Replica Divergence in a Weak-Consistency Protocol for Global-Scale Distributed Data Bases

this paper. Reference

An Efficient Implementation of Interactive Video-on-Demand

The key performance bottleneck for a video-on-demand (VOD) server is bandwidth, which controls the number of clients the server can simultaneously support. Previous work has shown that a strategy called stream tapping can make efficient use of bandwidth when clients are not allowed to interact (through VCR-like controls) with the video they are viewing. Here we present an interactive version of stream tapping and analyze its performance through the use of discrete event simulation. In particular, we show that stream tapping can use as little as 10% of the bandwidth required by dedicating a unique stream of data to each client request. Keywords: Interactive video on demand, bandwidth efficiency, stream tapping 1 Introduction Video-on-demand(VOD) is a service that allows clients to communicate with a VOD server to select and then view the video of their choice at the time of their choice. A few companies, such as IBM [17] and the DIVA Systems Corporation [8], are successfully running ..

Oasis: An active storage framework for object storage platform

The network bottleneck incurred by big data process and transfer has increasingly become a severe problem in today's data center and cloud. Exploring and exploiting the advantages of both the scalable object storage architecture and intelligent active storage technology are one of the ways to address this challenge. In this paper, we present the design and performance evaluation of Oasis, an active storage framework for object-based storage platform such as Seagate Kinetic. The basic idea behind Oasis is to leverage the OSD's processing capability to run data intensive applications locally. In contrast with previous work, Oasis has the following advantages. First, Oasis enables users to transparently process the OSD object and supports different processing granularity. Second, Oasis can ensure the integrity of execution code using signature scheme and provide the access control for the code execution in the OSD by enhancing the existing OSD security protocol. Third, Oasis can partition the computation task between host and OSD dynamically according to the OSD workload status. Our work on Oasis can be integrated into Kinetic object storage platform seamlessly. Experimental results on widely-used real world applications demonstrate the performance and efficiency of our system