Question: Shard the set of files into multiple directories

https://github.com/google/leveldb/blob/master/doc/impl.md#number-of-files
> Number of files
> Instead of always making 2MB files, we could make larger files for larger levels to reduce the total file count, though at the expense of more bursty compactions. Alternatively, we could shard the set of files into multiple directories.

Just wanted to know **how** can we shard the set of files into multiple directories as mentioned above. Is it somewhere in the configuration, setup... Any help or a documentation link on this would be much appreciated.