Round-like behavior in multiple disks on a bus

Rakesh Barve, Phillip B. Gibbons, Bruce K. Hillyer, Yossi Matias, Elizabeth Shriver, Jeffrey Scott Vitter

Research output: Contribution to conferencePaperpeer-review

Abstract

In modern I/O architectures, multiple disk drives are attached to each I/O bus. Under I/O-intensive workloads, the disk latency for a request can be overlapped with the disk latency and data transfers of requests to other disks, potentially resulting in an aggregate I/O throughput at nearly bus bandwidth. This paper reports on a performance impairment that results from a previously unknown form of convoy behavior in disk I/O, which we call rounds. In rounds, independent requests to distinct disks convoy, so that each disk services one request before any disk services its next request. We analyze log files to describe read performance of multiple Seagate Wren-7 disks that share a SCSI bus under a heavy workload, demonstrating the rounds behavior and quantifying its performance impact.

Original languageEnglish
Pages1-9
Number of pages9
DOIs
StatePublished - 1999
Externally publishedYes
EventProceedings of the 1999 6th Workshop on I/O in Parallel and Disbributed Systems, IOPADS '99 (The ACM Federated Computing Research Conference, FCRC'99) - Atlanta, GA, USA
Duration: 5 May 19995 May 1999

Conference

ConferenceProceedings of the 1999 6th Workshop on I/O in Parallel and Disbributed Systems, IOPADS '99 (The ACM Federated Computing Research Conference, FCRC'99)
CityAtlanta, GA, USA
Period5/05/995/05/99

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