file unexpected auto-cleaned when using rocksdb

[XuewanZhao]

When I use ardb, store engine is rocksdb. My data files are unexpected auto-cleaned. Is there anything wrong with my configuration?

rocksdb.options write_buffer_size=512M;max_write_buffer_number=20;min_write_buffer_number_to_merge=3;compression=kSnappyCompression;
bloom_locality=1;memtable_prefix_bloom_size_ratio=0.1;
block_based_table_factory={block_cache=512M;filter_policy=bloomfilter:10:true};
create_if_missing=true;max_open_files=15000;rate_limiter_bytes_per_sec=200M;
use_direct_io_for_flush_and_compaction=true;use_adaptive_mutex=true

other configurations are set as default.