Performance and design evaluation of the RAID-II storage server

RAID-II is a high-bandwidth, network-attached storage server designed and implemented at the University of California at Berkeley. In this paper, we measure the performance of RAID-II and evaluate various architectural decisions made during the design process. We first measure the end-to-end performance of the system to be approximately 20 MB/s for both disk array reads and writes. We then perform a bottleneck analysis by examining the performance of each individual subsystem and conclude that the disk subsystem limits performance. By adding a custom interconnect board with a high-speed memory and bus system and parity engine, we are able to achieve a performance speedup of 8 to 15 over a comparative system using only off-the-shelf hardware.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44815/1/10619_2005_Article_BF01266330.pd

A Trace-Driven Analysis of Name and Attribute Caching in a Distributed System

This paper presents the results of simulating file name and attribute caching on client machines in a distributed file system. The simulation used trace data gathered on a network of about 40 workstations. Caching was found to be advantageous: a cache on each client containing just 10 directories had a 91% hit rate on name lookups. Entry-based name caches (holding individual directory entries) had poorer performance for several reasons, resulting in a maximum hit rate of about 83%. File attribute caching obtained a 90% hit rate with a cache on each machine of the attributes for 30 files. The simulations show that maintaining cache consistency between machines is not a significant problem; only 1 in 400 name component lookups required invalidation of a remotely cached entry. Process migration to remote machines had little effect on caching. Caching was less successful in heavily shared and modified directories such as /tmp, but there weren't enough references to /tmp overall to affect t..

Oral mucosal microvascular network abnormalities in de novo mutation achondroplasia

Approximately 90% of achondroplasia (ACH) cases are the result of a de novo mutation, with no phenotypical markers for the unaffected ACH parents being known to date. Here, the hypothesis of the presence of an oral mucosal microvascular abnormality in ACH children and unaffected ACH parents was tested. Two-dimensional vascular network geometry was analyzed in 15 children with sporadic ACH, 30 unaffected parents of children with typical ACH phenotype, and 45 control subjects, using high-resolution photographs of the lower gingival and vestibular oral mucosa. The vascular networks of ACH patients and ACH parents exhibited higher D(1-46) (P 0.62 showed 100%-sensitivity and 100%-specificity in identifying unaffected ACH parents. These findings indicate (1) how complexity measures can be used to discover biological differences not demonstrable with traditional measures, and (2) the presence of a previously unrecognized microvascular network abnormality in both ACH patients and unaffected parents of children with de novo mutation ACH

Abstract Measurements of a Distributed File System

We analyzed the user-level file access patterns and caching behavior of the Sprite distributed file system. The first part of our analysis repeated a study done in 1985 of the BSD UNIX file system. We found that file throughput has increased by a factor of 20 to an average of 8 Kbytes per second per active user over 10-minute intervals, and that the use of process migration for load sharing increased burst rates by another factor of six. Also, many more very large (multi-megabyte) files are in use today than in 1985. The second part of our analysis measured the behavior of Sprite’s main-memory file caches. Client-level caches average about 7 Mbytes in size (about one-quarter to onethird of main memory) and filter out about 50 % of the traffic between clients and servers. 35 % of the remaining server traffic is caused by paging, even on workstations with large memories. We found that client cache consistency is needed to prevent stale data errors, but that it is not invoked often enough to degrade overall system performance. 1

Performance and Design Evaluation of the RAID-II Storage Server

: RAID-II is a high-bandwidth, networkattached storage server designed and implemented at the University of California at Berkeley. In this paper, we measure the performance of RAID-II and evaluate various architectural decisions made during the design process. We first measure the end-to-end performance of the system to be approximately 20 MB/s for both disk array reads and writes. We then perform a bottleneck analysis by examining the performance of each individual subsystem and conclude that the disk subsystem limits performance. By adding a custom interconnect board with a high-speed memory and bus system and parity engine, we are able to achieve a performance speedup of 8 to 15 over a comparative system using only off-theshelf hardware. 1 Introduction RAID-II is a high-bandwidth, network file server designed and implemented at the University of California at Berkeley as part of a project to study high-performance, large-capacity, highly-reliable storage systems. RAID-II is desig..