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home · events · colloquia · 1997-1998 · 
 

Colloquium - Wang

 
3/30/1998
10:00am-11:00am
ECCS 128

Surviving the I/O Blind Spots
University of California, Berkeley

I start this talk by asking two simple questions: 1) What is the minimum latency of transferring a file block over the network? 2) What is the minimum latency of writing a file block to disk?

These questions arise naturally as network attached storage systems are converging towards a common architecture that seeks to exploit the fast switched networks and the aggregate resources of a cluster. Although deceptively simple, these questions represent two important I/O blind spots that are not well understood. In the process of answering these questions, I first present a general pipeline theory for minimizing communication latency. Then I describe a new file system paradigm based on a programmable embedded disk processor (IDISK).

Although pipelining is a well known latency reduction technique, little research exists to guide the construction of optimal fragmentation algorithms. In the first half of my talk, I present a framework that can lead to a complete theory of optimal communication pipelines. I demonstrate several important optimality criteria. I provide a methodology that systematically uncovers communication pipeline parameters and constructs customized pipeline algorithms. I demonstrate significant performance improvement by applying the model to the Myrinet-GAM system.

Existing file systems suffer from two common fundamental assumptions that handicap their designs: that a small disk write is intrinsically expensive and that reorganizing the disk layout is a heavy-weight operation. By dedicating part of the storage management to the intelligent embedded disk processor, we are faced with the unique opportunity of rethinking a new file system paradigm based on low-latency persistent writes and light-weight reorganization. In the second half of the talk, I present the design and performance results of an IDISK-based file system.

Together, these two pieces form a synergy that allows one to craft a well-balanced I/O path and fully realize the performance potential of modern network file systems.


The Department holds colloquia throughout the Fall and Spring semesters. These colloquia, open to the public, are typically held on Thursday afternoons, but sometimes occur at other times as well. If you would like to receive email notification of upcoming colloquia, subscribe to our Colloquia Mailing List. If you would like to schedule a colloquium, see Colloquium Scheduling.

Sign language interpreters are available upon request. Please contact Stephanie Morris at least five days prior to the colloquium.

 
See also:
Department of Computer Science
College of Engineering and Applied Science
University of Colorado Boulder
Boulder, CO 80309-0430 USA
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