  The ALICE Muon IDentifier is composed of 72 single-gap bakelite Resistive
Plate Chambers, which have been operational since 2009 in maxi-avalanche mode
(discrimination threshold:7 mV without amplification) with a
Tetrafluoroethane/Isobutane/Sulfur Hexafluoride gas mixture, undergoing
counting rates of the order of tens of Hz/cm^2. In this talk, the long-term
performance and stability of the RPC system will be discussed, in terms of
efficiency, dark current and dark rate. An assessment of potential signs of
ageing observed on the detectors will be presented, together with a summary of
the most common hardware problems experienced.
