diff --git a/Amazon-S3-API.md b/Amazon-S3-API.md
index b5c3fab..3a76790 100644
--- a/Amazon-S3-API.md
+++ b/Amazon-S3-API.md
@@ -1,5 +1,6 @@
 To be compatible with Amazon S3 API, a separate "weed s3" command is provided. This provides much faster access when reading or writing files, compared to operating files on the cloud.
 
+# How it works?
 `weed s3` will start a stateless gateway server to bridge the Amazon S3 API to SeaweedFS Filer.
 For convenience, `weed server -s3` will start a master, a volume server, a filer, and the S3 gateway. And `weed filer -s3` can start a filer and the S3 gateway together also.
 
@@ -7,6 +8,24 @@ Each bucket is stored in one collection, and mapped to folder /buckets/<bucket_n
 
 A bucket can be deleted efficiently by deleting the whole collection.
 
+## Setup Notes
+
+Each bucket has its own collection. Usually one collection uses 7 volumes, where each volume is 30GB by default. So if you want to create multiple buckets, you may run out of volumes very quickly unless you have a large disk.
+
+Try to keep the volume size low. For example,
+```
+weed master -volumeSizeLimitMB=64
+```
+
+The other side is to reduce the number of volumes to create. In `weed shell`, you can configure this way:
+```
+$ weed shell
+> fs.configure -locationPrefix="/buckets/" -volumeGrowthCount=3 -apply
+
+```
+
+
+# Supported APIs
 Currently, the following APIs are supported.
 
 ```