{'fraction_non_alphanumeric': 0.02394526795895097, 'fraction_numerical': 0.002280501710376283, 'mean_word_length': 4.664516129032258, '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 New LSM-style Garbage Collection Scheme for ZNS SSDs

This paper explores how to design a garbage collection scheme for ZNS (Zoned NameSpace) SSDs (Solid State Drives). We first show that a naive garbage collection based on a zone unit incurs a long latency due to the huge size of a zone. To overcome this problem, we devise a new scheme, we refer to it as LSM ZGC (Log-Structured Merge style Zone Garbage Collection), that makes use of the following three features: segment based fine-grained garbage collection, reading both valid and invalid data in a group manner, and merging different data into separate zones. Our proposal can exploit the internal parallelism of a zone and reduce the utilization of a candidate zone by segregating hot and cold data. Real implementation based experimental results show that our scheme can enhance performance by 1.9 times on average.