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@@ -151,5 +151,10 @@ The last line shows the folder that already mounted something. Need to unmount i
 That should be it!
 
 ## Upgrade
+### How to change from 30GB version to large volume 8000G version?
+These two versions can not be mixed together.
+
+To change to a different version, you will need to manually copy the `.dat` files, and run `weed fix` to regenerate `.idx` files.
+
 ### How to upgrade from release 1.xx to a.yy
 Unless special notes, all upgrade will be backward compatible and ensure no data loss. There could be CLI tweaks. But in general, just test the CLI and make sure it can run.