On efficient wear leveling for large-scale flash-memory storage systems

Chang, Li-Pin

doi:10.1145/1244002.1244248

Cited by 219 publications

(115 citation statements)

References 5 publications

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“…SSD controller executes firmware, such as FTL, buffer management, ECC, etc. FTL is mainly responsible for three tasks: address mapping [32]- [34], garbage collection [35], [36], and wear-leveling [37], [38]. Flash memory controller manages the flash memory packages in each channel.…”

Section: Flash Memory and Ssdmentioning

confidence: 99%

Power Consumption Signature: Characterizing an SSD

Yoo

Lee

Won

2016

IEICE Trans. Inf. & Syst.

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SUMMARYSSDs consist of non-mechanical components (host interface, control core, DRAM, flash memory, etc.) whose integrated behavior is not well-known. This makes an SSD seem like a black-box to users. We analyzed power consumption of four SSDs with standard I/O operations. We find the following: (a) the power consumption of SSDs is not significantly lower than that of HDDs, (b) all SSDs we tested had similar power consumption patterns which, we assume, is a result of their internal parallelism. SSDs have a parallel architecture that connects flash memories by channel or by way. This parallel architecture improves performance of SSDs if the information is known to the file system. This paper proposes three SSD characterization algorithms to infer the characteristics of SSD, such as internal parallelism, I/O unit, and page allocation scheme, by measuring its power consumption with various sized workloads. These algorithms are applied to four real SSDs to find: (i) the internal parallelism to decide whether to perform I/Os in a concurrent or an interleaved manner, (ii) the I/O unit size that determines the maximum size that can be assigned to a flash memory, and (iii) a page allocation method to map the logical address of write operations, which are requested from the host to the physical address of flash memory. We developed a data sampling method to provide consistency in collecting power consumption patterns of each SSD. When we applied three algorithms to four real SSDs, we found flash memory configurations, I/O unit sizes, and page allocation schemes. We show that the performance of SSD can be improved by aligning the record size of file system with I/O unit of SSD, which we found by using our algorithm. We found that Q Pro has I/O unit of 32 KB, and by aligning the file system record size to 32 KB, the performance increased by 201% and energy consumption decreased by 85%, which compared to the record size of 4 KB.

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Section: Flash Memory and Ssdmentioning

confidence: 99%

Power Consumption Signature: Characterizing an SSD

Yoo

Lee

Won

2016

IEICE Trans. Inf. & Syst.

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“…If block B is the updated one, search new block B (step 6-8). After that, pick an empty block (step 9) and compare its erase cycles with both n A and n B (step [10][11][12][13][14][15][16][17]. Note that searching new P A or P B costs much time for huge-capacity systems, but as the frequency of updating block A or block B is very low and static wear leveling is not time critical when dynamic wear leveling exists, the time cost is acceptable.…”

Section: Methodsmentioning

confidence: 99%

Enhancing Endurance of Huge-Capacity Flash Storage Systems by Selectively Replacing Data Blocks

Wang

et al. 2012

IEICE Trans. Inf. & Syst.

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SUMMARYThe wear leveling is a critical factor which significantly impacts the lifetime and the performance of flash storage systems. To extend lifespan and reduce memory requirements, this paper proposed an efficient wear leveling without substantially increasing overhead and without modifying Flash Translation Layer (FTL) for huge-capacity flash storage systems, which is based on selective replacement. Experimental results show that our design levels the wear of different physical blocks with limited system overhead compared with previous algorithms.

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“…SD consists of dynamic and static phases for wear-leveling; in the dynamic phase, garbage collection is performed from the round-robin VEU queue, and in the static phase, hot-cold VEU swapping is performed. Dual-Pool (DP) performs data swapping between a young block and an old block similar to the Hot/Cold Swapping for wear-leveling [9]. Finally, Fast and endurant Garbage Collection (FeGC) has been proposed recently [1].…”

Section: Introductionmentioning

confidence: 99%

Practical Issues in Designing of Garbage Collection for Solid States Drives

Nam¹,

Kim²

2013

IJFCC

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Abstract-Due to out-of-place update property of NAND flash memory, garbage collection is required for NAND flash memory based SSDs (Solid-State Drives). In this paper, we discuss some practical issues on developing the garbage collection scheme. First, both efficiency and longevity should be considered together for garbage collection design. To this end, we present simple and effective victim block selection, hot/cold page classification, and free block management schemes. Second, the spatial and temporal overhead of garbage collection should be small for being employed on real systems. Finally, we discuss how to make use of the internal architecture of SSDs for garbage collection design. We implemented new garbage collection scheme that considers these all on real SSD platform. Through extensive experiments, we show that the proposed garbage collection scheme provides a good efficiency as well as expands the longevity of SSDs.

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On efficient wear leveling for large-scale flash-memory storage systems

Cited by 219 publications

References 5 publications

Power Consumption Signature: Characterizing an SSD

Power Consumption Signature: Characterizing an SSD

Enhancing Endurance of Huge-Capacity Flash Storage Systems by Selectively Replacing Data Blocks

Practical Issues in Designing of Garbage Collection for Solid States Drives

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