A method for controlling an apparatus to perform a multi-layer chemical mechanical polishing process with a polishing rate for a plurality of process runs. According to one aspect, a process repetitively performs the following steps as long as the process expects to receive at least one event message. An extended region for backup of the user data item is checked in response to a backup request. The polymer phase comprises hydroxypropylcellulose partially substituted by a substituent comprising a self-crosslinkable group, and is crosslinked through the self-crosslinkable group to form a polymer defining at least partially interconnected pores.