One embodiment disclosed relates to a method of preventative maintenance of a high-availability cluster. Two adjacent pressure chamber columns constituted by a first pressure chamber column and a second pressure chamber column are arranged opposite to each common ink path. An anti-reflective coating is provided on a surface of one of the first and second substrates. The extension portion is arranged on at least the front end of the body portion, and extends on the inner side generally perpendicular to the side window. A data record address is computed for the target data record utilizing the data record pointer and modulus. A base support is coupled to at least one of the first and second members.