{'fraction_non_alphanumeric': 0.0219435736677116, 'fraction_numerical': 0.003134796238244514, 'mean_word_length': 4.925729442970822, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
A Multi-Channel Redundant Check Storage Method for Solid-State Disks based on Cold and Hot Data Stripes

Solid-state disks (SSDs) with NAND Flash media are widely used in various aspects of data storage because of their fast read/write speed, low power consumption, and non-volatile and superior vibration resistance. Due to the inherent physical limitations of NAND Flash, the reliability of SSDs decreases greatly over time. A multi-channel redundant check storage technology based on cold and hot data stripes is proposed in this study to improve the reliability of the SSD without degrading read/write performance. First, this design proposed a storage array similar to Raid-4 built in the SSD whose inner storage array was partitioned into independent data and parity storage areas accommodating user data and parity information, respectively. Second, the flash translation layer (FTL) with different area management policies was established for two storage areas above. The data area and the parity area were used to store and manage user data and parity through their respective FTLs, including different address mapping, wear-leveling, and garbage collection methods. Finally, in the FTL of the parity area, the stripes were classified into cold stripes and hot stripes according to the updating times of each stripe. Therefore the cold stripe parity could be distinguished and directly written into the NAND Flash. The parity to the hot stripe was stored in the data buffer first and subsequently written into the NAND Flash when the hot stripe turned into a cold stripe. Results show that our proposed method improves the reliability and read/write performance of the SSD by establishing a Raid-4-like memory array inside the SSD. Meanwhile, applying dual FTLs and hot and cold stripe technology can reduce the page number of data erasure and write, thus improving the service life of the NAND Flash. Compared with the traditional Raid-5 array, the number of write parity in our design can be reduced by average 40%, and read/write performance improves over 30% at the same time. The study provides a new design for improving the reliability of SSDs, especially those with frequent write requests in practical applications.