Disadvantages Of Flash Memory

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As flash memory becomes popular, flash memory based solid state drive (SSD) has been the major storage device. SSD has numerous merits such as high I/O speed, low energy consumption, strong shock resistance and small form factor. Meanwhile, some shortcomings still exist including erase-before-write and different cost for read, write and erase operation. Aiming at efficient buffer management of SSD, this paper proposes a novel approach based on Particle Swarm Optimization (PSO) algorithm. The PSO algorithm is used to estimate the Predict Hot Fitness (PHF) value of each logical page in the buffer to correctly identify them either as hot or cold by properly reflecting the spatial and temporal locality. The pages predicted as hot are kept in the…show more content…
As the price of flash memory further drops and its capacity grows, the flash memory-based solid state drive (SSD) is getting more popular. Since it allows higher performance than the traditional hard disk drive (HDD) with much smaller power consumption, SSD is widely employed by mobile devices, personal computers, and even the servers of enterprise [3]. SSD has a number of advantages in terms of speed, power consumption, form factor, and shock resistance compared with HDD. HDD takes longer time for accessing the data because of the spinning of the disk plates, while there is no mechanical component with SSD. As a result, the speed of data access with SSD is over 100 times higher than HDD. Without moving parts, the rate of abrasion and failure are also much lower than…show more content…
First, a software layer called flash translation layer (FTL) has been developed [6]. Using the FTL, the logical block address (LBA) is mapped to physical block address (PBA) to allow effective management of the blocks in flash memory. Another solution is employing buffer cache of DRAM to store the data and mapping table [7]. There exist several advantages in employing buffer based on SSD. The response time is significantly reduced as the newly arriving data can be quickly stored. If the buffer is full, the selected victim pages are flushed out to flash memory. Various buffer management schemes have been proposed for SSD. Least recently used (LRU) is the most common scheme because of the simplicity and reasonable performance in any condition. However, selecting the victims based on only the recency cannot provide the best result for most of times. Clean first least recently used (CFLRU) [8] is an enhancement of LRU scheme where the modified pages are kept in the buffer to reduce the number of write operation with the SSD storage. Probabilistic Triplicate LRU (PTLRU) [16] is another scheme enhancing LRU, which keeps hot clean pages by flushing out cold clean

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