Hard-Disk Drives: The Good, the Bad, and the Ugly

Hard-disk drives (HDDs) are like the bread in a peanut butter and jelly sandwich-seemingly unexciting pieces of hardware necessary to hold the software. They are simply a means to an end. HDD reliability, however, has always been a significant weak link, perhaps the weak link, in data storage. In the late 1980s people recognized that HDD reliability was inadequate for large data storage systems so redundancy was added at the system level with some brilliant software algorithms, and RAID ( redundant array of independent disks) became a reality. RAID moved the reliability requirements from the HDD itself to the system of data disks. Commercial implementations of RAID include n+1 configurations