SnapMirror is a data replication technology that allows efficient and flexible data protection and disaster recovery for NetApp ONTAP storage systems1 SnapMirror transfers data between source and destination volumes using a network connection. SnapMirror can use storage efficiency features such as compression and deduplication to reduce the amount of data transferred and stored1 SnapMirror transfers are scheduled and controlled by policies that define the frequency, retention, and priority of the transfers. SnapMirror policies can also specify the network bandwidth limit for the transfers2 SnapMirror transfers are considered background tasks that run in the absence of user workload. SnapMirror transfers can consume CPU and disk resources on both source and destination systems, depending on the amount and type of data being replicated3 SnapMirror transfers can throttle up or down depending on the availability of system resources and network bandwidth. SnapMirror transfers will throttle up when there is no user workload, and throttle down when there is user workload. This is to ensure that SnapMirror transfers do not impact the performance of user operations3 Therefore, if a customer is concerned with high CPU and disk utilization on their SnapMirror destination system, the best answer is to explain that background tasks such as SnapMirror throttle up in the absence of user workload. This is normal and expected behavior, and it does not indicate a problem with the system3 Reference:
1: ONTAP 9 Data Protection - SnapMirror - The Open Group 2: ONTAP 9 Data Protection - SnapMirror Policies - The Open Group 3: SnapMirror storage efficiency configurations and behavior - Resolution Guide - NetApp Knowledge Base