Benchmarks are important because they provide a means for users and researchers to characterize how their workloads will perform on different systems and different system architectures. The field of file system design is no different from other areas of research in this regard, and a variety of file system benchmarks are in use, representing a wide range of the different user workloads that may be run on a file system. A realistic benchmark, however, is only one of the tools that is required in order to understand how a file system design will perform in the real world. The benchmark must also be executed on a realistic file system. While the simplest approach may be to measure the performance of an empty file system, this represents a state that is seldom encountered by real users. In order to study file systems in more representative conditions, we present a methodology for aging a test file system by replaying a workload similar to that experienced by a real file system over a period of many months, or even years. Our aging tools allow the same aging workload to be applied to multiple versions of the same file system, allowing scientific evaluation of the relative merits of competing file system designs. In addition to describing our aging tools, we demonstrate their use by applying them to evaluate two enhancements to the file layout policies of the UNIX fast file system.

In 1981, Stonebraker wrote: Operating system services in many existing systems are either too slow or inappropriate. Current DBMSs usually provide their own and make little or no use of those o ered by the operating system. [STON81] The standard operating system model has changed little since that time, and we believe that, at its core, it is the wrong model for DBMS and other resource-intensive applications. The standard model is in exible, uncooperative, and irregular in its treatment of resources. We describe the design of a new system, the VINO kernel, which addresses the limitations of standard operating systems. It focuses on three key ideas: Applications direct policy. Kernel mechanisms are reusable by applications. All resources share a common extensible interface. VINO's power and exibility make it an ideal platform for the design and implementation of traditional and modern database management systems. 1

Current operating systems are designed to provide leastcommon -denominator service to a variety of applications. They export few internal kernel facilities, and those which are exported have irregular interfaces. As a result, resource intensive applications such as database management systems and multimedia applications, are often poorly served by the operating system. These applications often go to great lengths to bypass normal kernel mechanisms to achieve acceptable performance. We describe a new kernel architecture, the VINO kernel, which addresses the limitations of conventional operating systems. The VINO design is driven by three principles: ffl Application Directed Policy: the operating system provides a collection of mechanisms, but applications dictate the policies applied to those mechanisms. ffl Kernel as Toolbox: applications can reuse the kernel's primitives. ffl Universal Resource Access: all resources are accessed through a single, common interface. VINO's power and...

To Maddie, who didn’t understand why Daddy had to work late And to Jackie, who did A fundamental problem with the current generation of file system benchmarks is that they fail to take into account the fact that a file system’s performance can vary depending on the workload running on it. Many benchmarks attempt to reduce file system perfor-mance to a single number, producing a simplistic one-dimensional ordering of the sys-tems being tested. Although this may be useful for marketing literature, the performance of file systems in the real world is more complicated. Different workloads place different demands on the file system, and can result in different behavior from the underlying sys-tem. A file system that provides superior performance for a web server may have inferior performance when running a software development workload. In this dissertation I demonstrate that the “one size fits all ” approach of current file system benchmarks does not accurately predict the performance of different workloads on different file systems. I then present a new benchmarking methodology

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Lately, on-demand streaming multimedia applications have become very popular. Contemporary personal computers can handle the load imposed by such multimedia applications on the client side, but the potentially high number of concurrent users accessing a server represents a generic problem. The multimedia storage system is responsible for storage and retrieval of multimedia data from storage devices, and plays a vital role for the performance and scalability of multimedia servers. It deals with issues related to data placement, scheduling, file management, continuous data delivery, buffer management, prefetching, etc., and with the particular demands of multimedia applications, such as real-time characteristics, large file sizes, high data rates, and several data sources. Performing these tasks and supporting these requirements appropriately are burdened by an increasing speed mismatch between processors and the most prolific and affordable storage devices, -- magnetic disks --, and by the introduction of new requirements in new multimedia scenarios.