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Mass Storage Systems and Technologies, IEEE / NASA Goddard Conference on (2010)
Incline Village, NV, USA
May 3, 2010 to May 7, 2010
ISBN: 978-1-4244-7152-2
pp: 1-12
Yang Hu , University of Science and Technology
Hong Jiang , University of Nebraska-Lincoln
Dan Feng , Wuhan National Laboratory for Optoelectronics
Lei Tian , Wuhan National Laboratory for Optoelectronics
Shuping Zhang , Institute 706 Second Academy of CASIC
Jingning Liu , University of Science and Technology
Wei Tong , Wuhan National Laboratory for Optoelectronics
Yi Qin , University of Science and Technology
Liuzheng Wang , Wuhan National Laboratory for Optoelectronics
Flash Translation Layer (FTL) is one of the most important components of SSD, whose main purpose is to perform logical to physical address translation in a way that is suitable to the unique physical characteristics of the Flash memory technology. The pure page-mapping FTL scheme, arguably the best FTL scheme due to its ability to map any logical page number (LPN) to any physical page number (PPN) to minimize erase operations, cannot be practically deployed since it consumes a prohibitively large RAM (SRAM or DRAM) space to store the page-mapping table for an SSD of moderate to large size. Alternatives to the pure page-mapping FTL, such as block-mapping FTLs, hybrid FTLs (e.g., FAST) and the latest demand-based page-mapping FTLs (e.g., DFTL), require significantly less RAM space but suffer from a few performance issues. Block-mapping FTLs perform poorly with higher erasure counts, particularly under random write workloads. Hybrid FTL schemes incur costly merge operations that hurt performance and increase the erasure counts. Performances of demand-based FTLs heavily depend on workload characteristics such as access locality, read/write ratio and request arrival interval time. This paper proposes a new FTL scheme, called HAT, to achieve the performance of a pure page-mapping FTL at the RAM cost of a block-mapping FTL while consuming lower energy, by hiding the address translation (HAT). The basic idea behind our scheme is to create a separate access path to read/write the address mapping information to significantly Hide the Address-Translation latency by incorporating a low energy-consuming solid-state memory device that stores the entire page mapping table. We implement an SSD simulator, SSDsim, to validate our HAT design and evaluate its performance. The extensive trace-driven simulation results show that the performance of HAT is within 0.8% of the pure page-mapping FTL, while consuming about 50% of the energy.

Y. Qin et al., "Achieving page-mapping FTL performance at block-mapping FTL cost by hiding address translation," 2010 IEEE 26th Symposium on Mass Storage Systems and Technologies (MSST 2010)(MSST), Incline Village, NV, 2010, pp. 1-12.
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