3.6.4 Remote copy Click  Remote Copy  to open the window that is shown in Figure 3-78. This window shows the  existing remote copy relationships, and you can set up and modify consistency groups. From  this window, you can also start and stop relationships, add relationships to a consistency  group, and switch the direction of the mirror. Figure 3-78 Remote Copy window The menu provides the options to create Metro Mirror, Global Mirror, or Global Mirror with  Changed Volumes: Metro Mirror This option makes  synchronous  copies. The original write operations  are not considered complete until the write operation to the destination  disk is confirmed. The distance between your two sites is determined  by how much latency your applications can handle. Global Mirror This option makes  asynchronous  copies of your disk. The write is  considered complete after it is complete at the local disk. It does not  wait for the write to be confirmed at the remote cluster as Metro Mirror  does. This method greatly reduces the latency that is experienced by  your applications if the other cluster is far away.  However, it also means that during a failure, the data on the remote  copy might not contain the most recent changes that were committed  to the local disk. Global Mirror with Changed Volumes This option is best described as “Continuous Remote FlashCopy.” If  you use this feature, IBM Spectrum Virtualize essentially takes a  periodic FlashCopy of a disk and writes it to your remote destination.  This feature completely isolates the local copy from wide area network  (WAN) issues and from sudden spikes in workload that might occur. The drawback is that your remote copy might lag behind the original  by a significant amount of data, depending on how you set up the  cycle time. Chapter 3. Graphical user interface overview  141