Protecting Data Against Early Disk Failures

Abstract

Disk drives are known to fail at a higher rate during their first year of operation than during the remaining years of their useful lifetime. We propose to use the free space that normally exists on new disks to minimize the risk of data loss during that first year. Our technique applies to disk arrays that mirror their data on two disks. Whenever a disk fails, the array will reorganize itself by storing a new copy of the disk that failed on one or more disks that have free space. This will protect the data against any single disk failure until the failed disk gets replaced and the system reverts to its original state. A Markov analysis of the behavior of a small system consisting of two pairs of mirrored disks indicates that our technique can reduce the probability of a data loss during the first year of operation of the system by at least 75 percent provided the disks have 34 percent of spare space.