Created Migrate to Filer Store (markdown)

Migrate-to-Filer-Store.md

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+If there are already a lot of files, how to move them to the SeaweedFS the most efficient way?
+
+### 1. Setup Filer
+1. create a filer.toml file, see the output of "weed scaffold -config=filer"
+1. choose and setup a filer data store. It is OK to just pick one and use it. You can always switch later. For example: `weed filer.export -sourceStore=mysql -targetStroe=cassandra`
+3. start the filer
+> Example: `weed filer -master=localhost:9333`
+
+### 2. Mount
+* start the "weed mount"
+> Example: `weed mount -filer=localhost:8888 -dir=/some/dir`
+
+### 3. Copy Files
+The easiest way is just to use the OS-provided copy command from the command line. However, usually it is single-threaded.
+
+The most efficient way is to use "weed filer.copy". It is multi-threaded and bypasses the FUSE layer.
+> Example: `weed filer.copy file_or_dir1 [file_or_dir2 file_or_dir3] http://localhost:8888/path/to/a/folder/`