diff --git a/manual/config/seafile-conf.md b/manual/config/seafile-conf.md
index bbcf5609..df93b2e7 100644
--- a/manual/config/seafile-conf.md
+++ b/manual/config/seafile-conf.md
@@ -142,7 +142,11 @@ max_sync_file_count = 100000
 fs_id_list_request_timeout = 300
 ```
 
-New in Seafile Pro 8.0.5: If you use cloud storage backend, you can enable the `use_block_cache` configuration to speed up file access. `use_block_cache` the default value is false. Note that this configuration is only effective for downloading files through web page or API, not for synchronized files. The `block_cache_size_limit` configuration is used to limit the size of the cache. `block_cache_size_limit` the default value is 10GB. the `block_cache_file_types` configuration is used to limit the file types that are cached. `block_cache_file_types` the default value is mp4;mov.
+If you use object storage as storage backend, when a large file is frequently downloaded, the same blocks need to be fetched from the storage backend to Seafile server. This may waste bandwith and cause high load on the internal network. Since Seafile Pro 8.0.5 version, we add block caching to improve the situation. Note that this configuration is only effective for downloading files through web page or API, but not for syncing files.
+
+* To enable this feature, set `use_block_cache` option in the `[fileserver]` group. It's not enabled by default. 
+* The `block_cache_size_limit` option is used to limit the size of the cache. Its default value is 10GB. The blocks are cached in `seafile-data/block-cache` directory. When the total size of cached files exceeds the limit, seaf-server will clean up older files until the size reduces to 70% of the limit. The cleanup interval is 5 minutes. You have to have a good estimate on how much space you need for the cache directory. Otherwise on frequent downloads this directory can be quickly filled up.
+* The `block_cache_file_types` configuration is used to choose the file types that are cached. `block_cache_file_types` the default value is mp4;mov.
 
 ```
 [fileserver]