Survey on High Density Magnetic Recording Technology

In the era of big data, the demand for large-capacity disks has been growing. With minimal technology changes to the existing disk head and storage media of hard disks, the shingled magnetic recording (SMR) technology is the best choice to increase the disk storage capacity. The interlaced magnetic recording (IMR) technology is a newly developed technology in recent years, which can achieve higher storage density and random write performance than SMR. In this paper, we first introduce the shingled track layout of SMR drive and the resulting write amplification problem. We also review the data management methods that mitigate write amplification problem, the evaluation of performance characterizations, and the research on SMR-based upper applications. Then we introduce the interlaced track layout of IMR drive and its data write amplification problem. We also analyze the future research topics of IMR drive. Finally, we compare SMR drive and IMR drive from the storage density, random write performance, and other aspects. A variety of SMR-based upper applications, like file system, database, and RAID, prove that SMR drive can be effectively used to replace conventional disks to build large-scale storage systems. The advantages of IMR drive over SMR drive will make it have a bright future.