Figure 1 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Source publication
The recent development of 3D flash memories has promoted the widespread application of SSDs in modern storage systems by providing large storage capacity and low cost. Garbage collection (GC) as a time-consuming but necessary operation in flash memories largely affects the performance. In this paper, we perform a comprehensive experimental study on...
Contexts in source publication
Context 1
... flash arrays in 3D SSDs are composed of 3D flash memory, which greatly increases the capacity of SSDs by vertically stacking multiple layers. Figure 1 illustrates the physical organization of flash cells in 3D flash memory. The control gates of the cells belonging to the same layer are connected together to form a wordline. ...
Context 2
... results would be presented in the following sections. Tail latency: Another quantitative evaluation of tail latency results with the 95th percentile and 99th percentile are presented in Figure 10. It can be observed that the two metrics have been significantly reduced by PreGC. ...
Context 3
... PreGC would migrate valid pages in advance before normal GC is invoked, the migrated pages might be updated during the pre-migration period and the victim block chosen in PreGC may not be the victim block in normal GC. Thus, PreGC would induce an extra write amplification, the results of which are shown in Figure 11. From the results, we can see that the write amplification for several traces is high but others are not. ...
Context 4
... section presents the performance result for more settings on key parameters in our implementation. Figures 12 and 13 show the comprehensive results when setting the threshold on free block proportion (T block ), and valid page ratio in a block (T page ). According to the results, three conclusions can be made. ...
Citations
... 2.1). Instead, the victim block will be added to the free block pool [26,49], and will be erased only when the system is idle [1,34,45]. Thus, duplicates are preserved in victim blocks. ...
Flash memory has been used extensively as external storage of smartphones, tablets, IoT devices, laptops, etc. Therefore, more and more sensitive or even mission critical data are stored in flash and, once the data turn obsolete, securely deleting them is necessary for both regulation compliance and privacy protection. Traditional secure deletion on flash memory mainly focuses on sanitizing data. However, unique nature of flash memory may cause various data "remnants" and, even though the data are removed, the remnants may be utilized by the adversary to recover the deleted data, compromising the secure deletion guarantee. Based on both theoretic analysis and experiments using real-world workloads, we have identified one common type of remnants in the flash memory, namely duplicates, which are caused by unique internal functions of flash storage media including garbage collection , wear leveling, bad block management. We propose RedFlash, a novel secure deletion scheme which can efficiently Remove both the data and the corresponding duplicates towards secure deletion on Flash memory. Security analysis and experimental evaluation show that RedFlash can ensure the secure deletion guarantee, at the cost of a small performance degradation, compared to a regular (non-secure) flash controller.
... This Special Issue provides insight on and advancements in Flash memory devices. There are nine papers including one review paper, covering the reliability of 3D NAND Flash devices [1][2][3], the characterization and design of Flash memory cell/string [2,4,5], NOR Flash memories for embedded applications [5], a set of Error Correction Codes and Secondary Correction Algorithms for flash memories [6,7], Flash management through flash signal processing in controllers for Big Data storage [6][7][8], and the impact of Flash memories on Solid State Drives reliability and performance [8,9]. ...
... The method has been validated on commercial off-the-shelf TLC 3D NAND Flash memory. In [9], Du et al. defined garbage collection (GC) as a time-consuming but necessary operation in Flash memories. They performed a comprehensive experimental study in view of a performance cliff that closely relates to Quality of Service (QoS). ...
Flash memory devices represented a breakthrough in the storage industry since their inception in the mid-1980s, and innovation is still ongoing after more than 35 years [...]
