Updated Directories and Files (markdown)

Directories-and-Files.md

@@ -45,10 +45,11 @@ visit "http://localhost:8888/path/to/sources/?lastFileName=abc.txt&limit=50"
 
 ## Architecture
 
+Filer has a persistent client connecting to Master, to know the locations of all volumes.
+
 For file reads:
 1. Filer lookup metadata from Filer Store, which can be Cassandra/Mysql/Postgres/Redis/LevelDB.
-2. Filer lookup the volume id locations if not in the cache.
-3. Filer read from volume servers and pass along to the read request.
+2. Filer read from volume servers and pass along to the read request.
 ![](FilerRead.png)
 
 For file writes: