A Review of Disc Scrubbing and Intra Disc Redundancy Techniques for Reducing Data Loss in Disc File Systems

Because of high demand that applications and new technologies have today for data storage capacity, more disk drives are needed, resulting in increased probability to inaccessible sectors, referred as Latent Sector Errors (LSE). Aiming to reduce data loss by LSE, two main techniques are extensively studied lately: Disk Scrubbing, which performs reading operations during idle periods on systems to search for errors and Intra Disk Redundancy which is based on redundancy codes. This paper reviews and discusses the problems of LSE and the main causes that lead to LSE, its properties and their correlation on nearline and enterprise disks. Focusing on reducing LSE with regards to security, processing overhead and disk space, we analyze and compare the latest techniques: Disc Scrubbing and Intra Disk Redundancy aiming to highlight the issues and challenges according to different statistical approaches. Furthermore, based on previous evaluation results, we discuss and introduce the benefits on using both schemes simultaneously: combining different IDR coding schemes with Accelerated Scrubbing and Staggered Scrubbing in particular regions of disc drives that store crucial data during idle periods. Finally, we discuss and evaluate from an extended statistical analysis the best ways on how reduce data loss with a minimum impact on system performance.