| According to Moore’s law, the rate of increase of magnetic recording densities is60%a year. However in recent years, traditional magnetic recording methods would reach alimit at around1Terabit/in2due to Superparamagnetic Effect. To further improve the arealdensity of magnetic hard disk drives, heat-assisted recording (HAMR) and bit patternedmedia (BPM) became the most popular technologies. But both technologies need toredesign the recording head or media, so they are far from practical application. Shingledwriting can improve the areal density by twice to three times and only need minor changeto the recording media and recording head. It still uses the conventional medium, so that itbecomes the most likely one of the practical technologies.Nevertheless, in shingled recording disk, when the data in one track is modified, thenearby tracks will be rewritten, which will cause data loss. A practicable way is that wecan remap the modified data in log structure. The shingled disk is divided into smallstorage units. In each unit, data is written continuously till the end of the unit. When thedata in a unit is to be modified, we simply allocate a new unit storage unit for the wholedata in the older unit, and move the modified data into the new unit. A mapping tablewhich maps the logic address into physical address is maintained by the storage software.Also the software will do the work of cleaning dirty storage units to usable ones.In the paper, I present a strategy to divide the disk into smaller storage units. In themapping strategy, the logic address is mapped into physical address in the format ofsegment, zone, track, and sector. The simulation work is done in the PC via virtual blockdevice, to compare new shingled recording disk with traditional disk. And the experimentresults shows that using this strategy, the shingled recording disk will perform quite wellin random small read and write, and only get10%degradation in the case of big read andwrite. |
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