diff --git a/Erasure-Coding-for-warm-storage.md b/Erasure-Coding-for-warm-storage.md
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--- a/Erasure-Coding-for-warm-storage.md
+++ b/Erasure-Coding-for-warm-storage.md
@@ -1,4 +1,6 @@
-Warm data are accessed less frequently. To store them more efficiently, you can enable erasure coding.
+Usually data is hot when it is fresh, and are accessed very often. SeaweedFS normal volumes tries hard to minimize the disk operations, but it comes with a cost of loading indexes in memory. 
+
+However, data can become warm or cold after a period of time. They are accessed much less often. The high cost of memory is not cost-efficient for warm storage. To store them more efficiently, you can "seal" the data and enable erasure coding.
 
 ## Benefit
 * **Storage Efficiency**: SeaweedFS implemented RS(10,4), which allows loss of 4 shards of data with 1.4x data size. Compared to replicating data 5 times to achieve the same robustness, it saves 3.6x disk space.