A simple equation for estimating reliability of an N+1 redundant array of independent disks (RAID)

摘要: This paper develops an equation that provides a good approximation of the expected number double-disk failures (data losses) in (N+1) redundant array inexpensive disks (RAID) as function time. includes statistical bases for equation, sources error and inaccuracies due to approximations, limitations its use. The is simple can be evaluated using hand held calculator or basic spreadsheet. Accuracy depends on four input distributions, which include operational failures, failure restorations, latent defects, data scrubbing. Failure restoration distributions may represent non-homogeneous Poisson processes and, therefore, not have constant rates. Results equations are compared two other calculation methods, highly accurate Monte Carlo simulation, actual field more than 10,000 RAID groups composed 14 drives.