|   | CMU-CS-01-146 Computer Science Department
 School of Computer Science, Carnegie Mellon University
 
    
     
 CMU-CS-01-146
 
Timing-accurate Storage Emulation 
John Linwood Griffin, Jiri Schindler, Steven W. Schlosser, Gregory R. Ganger
 
July 2001  
CMU-CS-01-146.psCMU-CS-01-146.pdf
 Keywords: Disk scheduling, storage systems
 Timing-accurate storage emulation fills an important hole in the set
of common performance evaluation techniques for proposed storage designs: 
it allows a researcher to experiment with not-yet-existing storage components 
in the context of real systems executing real applications. As its name 
suggests, a timing-accurate storage emulator appears to the system to 
be a real storage component with service times matching a simulation model 
of that component. This paper promotes timing-accurate storage emulation 
by describing its unique features, demonstrating its feasibility, and 
illustrating its value. A prototype, called the Memulator, is described 
and shown to produce service times within 2% of those computed by its 
component simulator for over 99% of requests. Two sets of measurements 
enabled by the Memulator illustrate its power: (1) application performance
on a modern Linux system equipped with a MEMS-based storage device (no 
such device exists at this time), and (2) application performance on a 
modern Linux system equipped with a disk whose firmware has been modified 
(we have no access to firmware source code).
 
26 pages 
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