User and group quotas leverage the identity mapping service on the appliance. This allows users and groups to be specified as either UNIX or Windows identities, depending on the environment. Like file ownership, these identities are tracked in the following ways:
If there is no UNIX mapping, a reference to the windows ID is stored.
If there is a UNIX mapping, then the UNIX ID is stored.
This means that the canonical form of the identity is the UNIX ID. If the mapping is changed later, the new mapping will be enforced based on the new UNIX ID. If a file is created by a Windows user when no mapping exists, and a mapping is later created, new files will be treated as a different owner for the purposes of access control and usage format. This also implies that if a user ID is reused (i.e. a new user name association created), then any existing files or quotas will appear to be owned by the new user name.
It is recommended that any identity mapping rules be established before attempting to actively use filesystems. Otherwise, any change in mapping can sometimes have surprising results.