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@@ -54,7 +54,7 @@ It is also important to leave some disk space for a couple of volume size, so th
 
 If one volume has large number of small files, the memory usage would be high in order to keep each entry in memory or in leveldb.
 
-To reduce memory usage, one way is to convert the older volumes into Erasure-Coded volumes, which are read only. The volume server can will sort the index and store it as a sorted index file (with extension `.sdx`). So looking up one entry costs a binary search within the sorted index file, instead of O(1) memory lookup.
+To reduce memory usage, one way is to convert the older volumes into [Erasure-Coded volumes](https://github.com/chrislusf/seaweedfs/wiki/Erasure-Coding-for-warm-storage), which are read only. The volume server can will sort the index and store it as a sorted index file (with extension `.sdx`). So looking up one entry costs a binary search within the sorted index file, instead of O(1) memory lookup.
 
 ### How to configure volumes larger than 30GB?