.set_flags(NO_SYNC | NO_TLS)
            // 2 DBs; one for file contents, one for leases.
            .set_max_dbs(2)
            .set_map_size(MAX_LOCAL_STORE_SIZE_BYTES / 16)
            .open(&dir)
            .map_err(|e| format!("Error making env for store at {:?}: {:?} for ", dir, e))?;