Paper Info
Title
Beyond MTTDL: A Closed-Form RAID 6 Reliability Equation
Abstract
We introduce a new closed-form equation for estimating the number of data-loss events for a redundant array of inexpensive disks in a RAID-6 configuration. The equation expresses operational failures, their restorations, latent (sector) defects, and disk media scrubbing by time-based distributions that can represent non-homogeneous Poisson processes. It uses two-parameter Weibull distributions that allows the distributions to take on many different shapes, modeling increasing, decreasing, or constant occurrence rates. This article focuses on the statistical basis of the equation. It also presents time-based distributions of the four processes based on an extensive analysis of field data collected over several years from 10,000s of commercially available systems with 100,000s of disk drives. Our results for RAID-6 groups of size 16 indicate that the closed-form expression yields much more accurate results compared to the MTTDL reliability equation and matching computationally-intensive Monte Carlo simulations.
Year
DOI
Venue
2014
10.1145/2577386
TOS
Keywords
Field
DocType
raid-6 configuration,disk media,inexpensive disk,closed-form raid,mttdl reliability equation,reliability equation,raid-6 group,new closed-form equation,disk drive,accurate result,beyond mttdl,time-based distribution,closed-form expression yield
Monte Carlo method,Field data,Computer science,Weibull distribution,Real-time computing,Poisson distribution,RAID,Data scrubbing
Journal
Volume
Issue
ISSN
10
2
1553-3077
Citations 
PageRank 
References 
12
0.62
15
Authors
2
Name
Order
Citations
PageRank
Jon G. Elerath1613.67
Jiri Schindler241126.82