When you're using your Synology exclusively as a iSCSI target, and have assigned the complete disk space to your LUN's, you will get notifications about the volume being (almost) completely full. Obviously, in this case, you may not want to receive these notifications. Luckily, you can turn these off:
Note that this will only disable the notifications (e-mail, SMS, etc.). The widget and WebUI will still show the alerts.
It's possible for Synology devices running DSM 3 or higher to enable support for NTFS ACL's. This allows Windows-users to set up Security through Windows Explorer itself. Most of the ACL types are supported.
NTFS ACL's have to be enabled for a share through the web-interface: