improved readme

README.md

@@ -11,6 +11,8 @@ connect per ssh to the device, then run these commands (replace the seek=100G wi
 ```bash
 dd if=/dev/zero of=storage bs=1 count=0 seek=100G
 
+chmod go-rwx storage
+
 sudo cryptsetup luksFormat storage
 
 sudo cryptsetup luksOpen storage luks_setup
@@ -34,6 +36,8 @@ rmdir backup
 
 you can replace the name (`storage`) with any filename you like. If you'd rather use a partition skip the `dd` part and run `luksFormat` directly on your partition and replace the file with the device at all other steps.
 
+*Note that the file will be shown to be 150GB in size, but it will not use 150GB of disk space. As the luks container fills up, the file will grow with it. If you don't want this, I would suggest filling the whole file with data from urandom. This will take a while on initialization though.*
+
 **step 2:** configure the backup script:
 Replace these variables in the beginning with your own: