As the LUN mapping sequence is changed on the disk array, the LUN mapping sequence on each host may be changed. The specific mapping policy is implemented by the PCM KE driver of the AIX OS. What is the risk caused by the inconsistent mappings? In the two-node mode, if the LUN mapping sequences are inconsistent on two host, check whether upper-layer applications are based on block device (hdiskX or updiskX) or file system. If upper-layer applications are based on file system, inconsistent LUN mapping sequences have no impact on the applications. If upper-layer applications are based on block device, the actually used LUNs are not the mapped LUNs as the mappings between block devices and LUNs have changed. Therefore, applications encounter errors.